|I don't know what's right anymore. But the only choice for me now...is to face the consequences of my actions...and as a Warrior...fulfill my duty to the bitter end!|
|— Reiner proclaims his resolve|
Reiner Braun (ライナー・ブラウン Rainā Buraun?) is a graduate of the 104th Cadet Corps and a former member of the Scout Regiment. He ranked 2nd in his class and was regarded by others as a charismatic and a reliable big brother-like figure. He is rarely seen without Bertholdt Hoover, his close childhood friend, both of whom originate from an unknown area which he refers to as his hometown.
Along with Bertholdt and Annie Leonhart, he is a person that possesses the ability to transform into a Titan. He is the current holder of the Armored Titan. In the year 845, he used his power to help Bertholdt breach Wall Maria and infiltrate the military for currently unknown reasons.
Reiner has short blond hair, gold eyes, and a defined facial structure. His large height, broad shoulders, and serious expression give him an intimidating presence. As a member of the Scout Regiment, he wears the wings of freedom jacket over his standard military uniform, with a green shirt underneath. In casual attire, Reiner wears a dark gray button-down shirt with rolled up sleeves and dark green pants with a brown belt.
Reiner's Armored Titan form is 15 meters tall and has plates of hardened skin covering the entirety of its body, except for muscles in its cheeks that become exposed when it opens its lipless jaw, as well as the muscle tissue behind its knees, elbows, and feet. Its eyes are covered by white, organic lenses, and it has short, blond hair. While fighting Eren, it has been noted that it has high agility and is capable of moving at a fast momentum, despite its seemingly-heavy weight and being low on stamina.
Reiner is a passionate and honest person, with a strong sense of duty. He takes his role as a soldier very seriously and encourages others to do the same. However, he is also noted to have a kind heart and a tendency to always think of others before himself, taking on extra burdens for the sake of his comrades. He is stated to be the "big brother" of the other cadets.
However, he is also revealed to have serious emotional and mental problems as a result of his actions, he suffers from borderline personality disorder. While still loyal to his true cause as a Warrior, he was unable to cope with the guilt and has begun to suppress his true memories in an effort to escape. During these episodes, he forgets his true identity, believing himself to be a human soldier. There appear to be few differences between his "soldier" persona and his true self, though his true "Warrior" self is more ruthless and fatalistic out of necessity. Even so, he continually places himself at risk in an effort to reach out to Eren and Ymir, trusting them more than is wise.
In the year 845 Reiner set out on a mission to exterminate humanity and retrieve the Founding Titan, along with his childhood friends, Bertholdt Hoover, Annie Leonhart and Marcel, the wielders of the Colossal Titan, Female Titan and another Titan. On their journey, the four young Warriors were ambushed by a Titan slumbering in the earth that tried to devour Reiner. As he stood in fear, Reiner was almost killed until Marcel pushed him away but was grabbed and devoured instead while Reiner, Bertholdt, and Annie watched in horror.
Shortly after the Colossal Titan first breaches Wall Maria via Shiganshina District, Reiner assumes his Armored Titan form and enters the city and makes his way across it to the interior gate of Wall Maria. Once there, he charges towards the gate as several Garrison members try to stop him with cannon fire. However the cannons have no effect and Reiner quickly smashes through the wall, allowing the other Titans to swarm Wall Maria. At some point during the abandonment of Wall Maria he, Bertholdt and Annie passed themselves off as survivors of a small hunting village on the south side of Wall Maria to cover for their lack of family records, which the destruction of Wall Maria helped contribute to.
Shortly after the destruction of Wall Maria, Reiner and Bertholdt were among the many refugees that were informed of the food shortage.
Two years after the destruction of Wall Maria, in the year 847, Reiner enlists in the military and becomes a member of the 104th Cadet Corps along with Bertholdt and Annie. On the first day of training, Reiner is one of the few students who the instructor Keith Sadies does not attempt to haze, as he is able to tell that Reiner has already been through a rite of passage.
After failing repeatedly to operate the omni-directional mobility gear, Eren seeks advice from his fellow cadets and is sent to Reiner and Bertholdt for help by Marco Bodt. Though initially unfriendly towards Eren and Armin, Reiner and Bertholdt quickly warm up to them after learning they are from Shiganshina District and are still willing to enlist in the Scout Regiment. Reiner is especially impressed with Eren's will to enlist despite watching his mother being devoured by a Titan. He shares his desire to return to his lost hometown and agrees to give Eren advice. The next day they witness Eren's last attempt to pass where he fails yet again until Sadies notices that his equipment is defective. Upon being resupplied Eren passes the test as Reiner and Bertholdt watch impressed with Eren's determination.
Over the next three years, Reiner continued his training with his fellow cadets. Reiner was noted by Keith Sadies to have exceptional mental and physical fortitude, as well as a great ability to gain the confidence of his comrades. Eren also came to view him as a big brother to the 104th and came to idolize Reiner and aspired to be as strong as him one day. However the guilt of all the people who died because of him caused Reiner to develop physiological trauma and he developed dissociative identity disorder, developing an alter-ego that believed he really was a soldier and not a Warrior. Sometimes Reiner would not be able to remember who he really was until Bertholdt reminded him which saddened his friend.
At some point during their training, the cadets completed a snowstorm training exercise. However, Reiner quickly notes that Christa, Ymir, and Daz are still missing. Marco suggests they are with Thomas' squad but Reiner points out that his squad just completed their mission. The next morning when Eren, Mikasa, and Armin decide to go looking for them, Reiner and Bertholdt decide to accompany them, as well as Conny, Sasha, and Marco. However, they hear a loud almost thunder-like noise and head out to investigate but discover Ymir returning to camp with Daz who is tended to by the others indoors.
In 850 when partaking in a jogging exercise carrying supplies through a rainstorm Reiner notices Armin falling behind. Annoyed to see him fall behind from lack of physical strength Reiner takes his supplies and carries them and his own for a time, but Armin insists on doing it himself and takes back his supplies. Later during hand-to-hand combat training, he advises Eren to take his duty as a soldier seriously when he questions the use of hand-to-hand when their enemies are Titans. Noticing Annie attempting to sneak away from training, he intercepts her and goads her into sparring with Eren to test him. After seeing her easily dispatch Eren, he hesitates to take her on himself but is convinced to by Eren and is quickly defeated as well. Later Reiner watches Eren and Jean argue over Jean's selfishness to join the Military Police so he will not have to fight Titans, and is impressed when he see him use Annie's technique to put him in line. Eventually Reiner graduates 2nd in the class, finishing just behind Mikasa Ackermann.
In the year 848, Reiner is placed in a group of cadets led by Thomas Wagner to go on a wilderness hunt that will teach the cadets to sustain themselves in times of peace. When it is discovered that the group's ODM gear has been stolen, Reiner and Annie investigate the remnants of a campfire nearby, as well as numerous carriage tracks, and deduce that their gear must have been stolen by thieves. Thomas suggests ending the operation early, but Reiner insists that they speed up their progress so that they can warn the other team of cadets, led by Marco Bodt, before returning to the training grounds.
The next day, Reiner and his group come upon Marco's group, who have been engaging the kidnappers, and help them disarm the remaining men.
In the year 849, the 104th Cadets Corps participates in a mock defense mission in Trost District, to evaluate the cadets' abilities. After performing one mock operation with his fellow cadets, Reiner is present when Jean gets into a fight with Sasha and Conny for "stealing" his Titan kills during the mission. Reiner tries to point out that all of the Titans were free for anyone to kill, but is forced to step in when the altercation nearly devolves into a brawl. The argument is interrupted by Commander Dot Pyxis, who suggests that Sasha and Jean settle their differences with a cooking competition.
Reiner and Conny decide to help Sasha with her dish, and accompany her into the wilderness outside of Trost to search for a wild boar that has been reported, in order to cook it. Although they initially follow Sasha's nose to pursue the boar, Reiner begins to doubt they will be able to find it. He is proven wrong, as Sasha is able to successfully locate the boar, but upon seeing the size of it, insists that they leave it be. As he is attempting to leave, however, Sasha physically assaults him before breaking into tears that he would give up so quickly. Eager to make amends, Reiner apologizes and agrees to help, only for Conny to alert the two of them that their fighting has alerted the boar to their presence. They engage the boar, and Sasha manages to kill it.
After returning to Trost, Reiner helps Conny and Sasha prepare the boar's meat, and accompanies them to the competition to present it.
As part of the defensive effort of the military after the second attack of the Colossal Titan, Reiner is assigned to the front guard. However, with the supply team stuck in Trost's Military headquarters, he is essentially immobilized with many of his teammates on a rooftop. He and Annie discuss what to do next, with Reiner suggesting that they wait for the Titans to gather to them before they make a move. Mikasa asks them if they have seen Eren, and Reiner points out Armin, telling her he was in Eren's squad.
Mikasa takes charge, leading an attempt to get to the military headquarters in Trost, which Reiner takes part in. Upon reaching the headquarters, Reiner keeps watch, alerting his teammates when Titans begin to attack the building. Conny, Mikasa, and Armin arrive shortly afterward, with an abnormal Titan in tow that promptly begins to kill the Titans swarming the outside of the building. Alarmed by the Titan's behavior, Reiner tries to find out how much the three know about it but is unable to get any information out of them.
Reiner takes part in Armin's plan to clear out the smaller Titans that have infiltrated the headquarters' armory. After the Titans are lured together by the cadets and blinded via gunfire, he and six other cadets attack them, in an effort to clear out all of the Titans in one move. As the other cadets move out after resupplying, Reiner is among the soldiers that stay behind to observe the abnormal Titan as it is overwhelmed by the mindless Titans. Suspecting that the Titan is intelligent, Reiner, Annie, and Bertholdt argue that they should help it and prevent it from being eaten. They are silenced when the Titan breaks away from the Titans devouring it to kill one final Titan, before collapsing. They prepare to leave, but are shocked at the sight of Eren Jaeger emerging from the Titan's nape. Reiner, Jean, Annie, and Bertholdt are placed on standby with their fellow cadets, and are ordered not to tell anyone what they witnessed.
Later, after seeing what appears to be Titan vapor from inside the city, he and the soldiers that witnessed Eren's emergence from the Titan's nape scale the Wall to see what is happening. Over the Wall, they see Eren protecting Mikasa and Armin from cannon fire, with a shield made from the torso of his Titan form.
Later into the battle, Reiner, Bertholdt and Annie capture Marco and remove his omni-directional mobility gear. The three leave Marco stranded on a roof and watch in horror as a nearby Titan eats him.
In the aftermath of Trost, Reiner enlists in the Scout Regiment. During the 57th Exterior Scouting Mission, he comes across Armin, who has narrowly survived an encounter with the Female Titan and are soon joined by Jean. Reiner is surprised when Armin deduces the Female Titan is in a human Titan just like Eren, and that she is after someone specific. Armin deduces Eren but Reiner is confused after Armin and Jean tell Reiner that Eren and Levi Squad are in the left wing, as Reiner's copy of the scouting formation had them in the right wing. Reiner asks where Eren is meant to be and Armin deduces the rear of the center rank.
Reiner, Armin and Jean subsequently devise a plan to follow and attack the Female Titan to slow her down and allow the formation time to regroup. Before attacking Armin tells Reiner and Jean to pull their hoods all the way over to cover their faces knowing that she will not kill them if she does not know who they are, as any of them could easily be Eren. After Armin and Jean are injured Reiner attempts a direct attack while the Female Titan is distracted by Armin's false claims that Eren is dead. Reiner is grabbed by the Female Titan and seemingly crushed but in reality secretly carves a message into her palm telling her Eren's true whereabouts.
Afterward, Reiner tends to Armin's head wound while Jean attempts to call back his missing horse. The group is preparing to decide who to leave behind, when Christa Lenz, having followed their flares, arrives with two extra horses, saving them. Stunned by her timely rescue and beauty, Reiner mentally expresses the desire to marry her.
The group rejoins the main force soon after, though they are frustrated by Erwin Smith's decision to continue the doomed mission and the lack of information available. Assigned to stand by at the edge of the Forest of Giant Trees and act as bait for the Titans, Reiner repeatedly expresses concern about what is going on inside the forest. When the mission ends in failure, he returns to Wall Rose in poor spirits.
During the assault on Stohess District, several of the 104th Cadet Corps recruits including Reiner are kept on standby at an outpost south of Wall Sina. They are under the watch of Miche Zacharius and a number of Scout Regiment soldiers until further notice. Most of the recruits are bored and Reiner expresses suspicion over the real reason for their stay. They are out of uniform and not permitted to train, while the rest of the soldiers are fully equipped despite the fact they are inside the Walls and not on the frontline.
The mood quickly changes when Sasha announces that she hears footsteps and Nanaba arrives to tell them that Titans have been sighted and there is no time for them to gear up. They are to take their horses and evacuate all nearby homes and settlements under the assumption that Wall Rose has been breached. The veterans and recruits split into four teams and Reiner volunteers to go south with Conny's group and help him to his village, even though it is likely to be the most dangerous and closest to any possible breach.
When they arrive they find the village empty, though there is an oddly deformed Titan on top of Conny's house. Since there is no longer anyone in the village left to help, Gelgar changes their mission to locate the breach in the wall. As they prepare to leave, the Titan brokenly says "Welcome home," which freaks out Conny. Reiner snaps him out of it and pushes him to focus on the mission.
However, after patrolling along the Wall their team meets up with Christa and Ymir's without finding signs of any breach. The teams and their horses are exhausted so they decide to take refuge in Utgard Castle for the night. Gelgar has the rookies to get some rest while the veterans take turns keeping watch. When Ymir asks Conny how the trip to his village went, he tells her that it was destroyed, but at least no one was eaten, so they had likely escaped. He cannot stop thinking about the strangely immobile Titan on his house though. It reminds him of his mother. Reiner starts to tell him to stop thinking about it when Ymir breaks out with a mocking laugh. Her teasing irritates Conny enough to cause him to shut up about the subject.
Reiner later finds Ymir scavenging for food and thanks her for distracting Conny so he does not keep worrying about his family. Barely paying attention, Ymir finds a can of herring and Reiner asks if he can see it. When he looks at the strange lettering, he is surprised that Ymir can read it, but before he can press her for information, they are interrupted by the arrival of Titans and called to the top of the castle's tower. The soldiers are shocked to find themselves surrounded because Titans should not be active at night.
Lynne discovers some of the smaller Titans have breached the door at the bottom of the tower and instructs the rookies to go down and form a barricade while she, Gelgar, Henning, and Nanaba handle the ones outside. Reiner leads the charge, calling for the others to grab boards, rods, and whatever else they can get their hands on. Further down the tower, he opens a barred door and discovers a small Titan on the other side. He slams the door shut and calls for the others to bring something. Before anyone can, the Titan breaks an arm through the door and swipes at Reiner, triggering a childhood memory of when another Titan attacked him and a friend pushed him out of the way, sacrificing himself so that Reiner would live.
Bertholdt arrives and jams a pitchfork into the Titan. Together with Reiner, they force it back long enough for Christa, Ymir, and Conny to arrive with a cannon that they barrel down the stairs and into the Titan, pinning it to the floor. Before the group can head back upstairs, a second Titan emerges and attacks Conny. Reiner pushes him out of the way, but the Titan bites down on his arm. He grits his teeth and manages to lift the Titan over his shoulders and carries it to a window with the intention of jumping out with it. Conny uses his knife though and cuts open the jaw enough for Reiner to get his arm free before Ymir kicks it out.
Christa treats Reiner's arm and says it is probably broken and they will need a splint and bandages. She tears her skirt to wrap his arm and Conny doubts that he could ever be as brave as Reiner, who views his behavior as normal for a soldier. Conny asks Bertholdt if Reiner was always like this and Bertholdt says that in the past he was more of a Warrior, which confuses Reiner.
The battle outside goes poorly and the rookies join the veterans at the top of the tower in time to see them overwhelmed by a second wave of Titans. When Ymir transforms into a Titan to protect everyone, Reiner is stunned to recognize her as the Titan who ate Marcel five years ago. Ymir ends up bringing down the tower and asks everyone to grab on to her to escape. Hange's forces arrive shortly thereafter to finish off the remaining Titans.
The Scout Regiment takes stock of their injured on top of Wall Rose. Reiner is disturbed by how he could have died twice now; once to the Female Titan and another to the Titan in Utgard Castle. Eren is sympathetic and says they have been driven far away enough from their hometown, which triggers something in both Reiner and Bertholdt. Bertholdt suggests that it is almost time for them both to go home and a change comes over Reiner. He confesses to Eren that five years ago he and Bertholdt, the Armored and Colossal Titans respectively, broke down the Wall to destroy humanity, but that is no longer necessary if Eren comes with them.
Eren, however, is incredulous and insists that Reiner is just not thinking straight. Reiner comes to the conclusion that he has been living a lie for too long. He does not know what is right anymore, but he can face the consequences of his actions as a Warrior. Reiner undoes the sling around his broken arm to show it completely healing, revealing that he does indeed have the power of the Titans.
Mikasa injures Reiner and Bertholdt before they can take Eren, but Reiner shoves her off the Wall when she tries to finish off Bertholdt. With the injuries they have sustained, both Reiner and Bertholdt transform into their respective Titans. The Scout Regiment tries to rescue Eren, but they are kept at bay by the Colossal Titan's steam. Reiner grabs a visibly shocked and betrayed Eren and descends down the wall. However, Eren bites his own hand to change into a Titan and breaks free.
The two engage in combat, and Reiner proves significantly stronger. He punches Eren across the field and though Eren regenerates multiple times, Reiner continues to beat him down. After getting back to his feet a third time, Eren charges Reiner once more as Reiner attempts another attack. However, Eren does not try to punch him. Instead he uses a technique Annie taught him. He locks his arms around Reiner and throws him to the ground. Reiner manages to break free of the initial hold, but Eren wraps his legs around the former's neck and squeezes his neck into his shoulder, causing his armor to crack. Eren then forces Reiner to the ground while applying more pressure to Reiner's right arm until it finally breaks and is torn out of the socket.
Eren then falls back to the wall as Reiner slowly follows but suddenly increases speed by shedding armor around his legs and charges towards Eren. He slams Eren into the wall and begins to repeatedly punch him. Realizing that dodging Reiner's attacks would be impossible, Eren allows himself to be tackled but wraps his arms and legs around Reiner's back and begins to squeeze. While they are locked in place, Mikasa uses swoops down and slices through the exposed Titan flesh behind his left leg where he would shed his armor leaving him almost immobile. Eren then starts squeezing harder until Reiner's armor begins to shatter once more, trying to tear him out of his Titan form. However, Reiner starts using his intact left arm to crawl back to the spot they landed and roars to Bertholdt, who then falls on them both.
With Bertholdt's assistance, Reiner is able to defeat Eren and bites him out of his Titan body. He and Bertholdt flee to a nearby forest of giant trees where they hold him and Ymir captive while they recover in preparation for their escape to Wall Maria. Reiner suffers from a case of mental dissonance where he lapses back into his persona as a soldier, commenting on how fortunate it is that Wall Rose was not actually broken and how they all should be promoted, until Bertholdt snaps him out of it by reminding him that he is a Warrior. This causes him to remember his involvement in Marco's death during the Struggle for Trost.
When Ymir starts talking Eren down from his latest bout of anger, she comes close to revealing more information than Reiner would like, so he offers her a deal to side with them. They might not be able to help Ymir specifically, but Reiner says they can still look after Christa. Ymir accepts and says nothing further to Eren.
He and Bertholdt prepare to leave once they spot the Scout Regiment's signal flares. Before they depart Reiner tells Betholdt once their mission is complete he needs to tell Annie how he feels about her. Bertholdt is embarrassed at his suggestion but Reiner admits he is known about his crush for sometime, and believes Bertholdt should go for it. Reiner restrains Eren and flees together with Bertholdt and Ymir, but Ymir insists on going back for Christa and threatens to ruin their escape unless they accommodate her. They wait long enough for her retrieve Christa, then Reiner transforms into the Armored Titan and begins running away from the forest with the rest of the group riding on his shoulders.
Despite their head start, a small group of soldiers catches up with them and begins to attack. Reiner protects Bertholdt and the captive Eren by covering them with his hands as they shelter under his chin. The other members of the 104th try talking to him and Bertholdt, but they scatter when Erwin leads a horde of Titans towards them. Reiner brings his head down and charges into them, but it is not enough to break through. Enough Titans grab him that he eventually immobilized.
Knowing that he will eventually be worn down, Reiner removes his hands from his throat and punches back the Titans, but this exposes Bertholdt and Eren to attack. During the fighting Armin lands on Reiner's head and asks them why they are leaving Annie behind. He claims she is being tortured, which provokes Bertholdt and allows Erwin a chance to free Eren. The soldiers flee while Reiner is still trying to remove the Titans around him.
He begins throwing the removed Titans at the fleeing soldiers, seemingly no longer caring if Eren is eaten. Reiner manages to knock both Eren and Mikasa off their horses, leaving them to face a particular Titan. While the Scouts battle among the chaos Reiner continued shaking Titans off him trying to reach Eren. In a moment of desperation, Eren punches the Titan and screams. The sound reverberates through Reiner, Bertholdt, and Ymir as the smaller Titans rush in and devour the one Eren had faced.
Reiner realizes that Eren holds the Founding Titan and he is the worst person imaginable to possess it. He charges at Eren, but Eren screams that he will kill them. This triggers another reaction in Reiner and Bertholdt, and the other Titans turn to attack them. There are too many for Reiner to adequately protect Bertholdt by himself, but Ymir comes back to help them.
After the battle, the three catch their breath on top of Wall Maria, having managed to survive. Reiner asks Ymir why she bothered to save them and she says that she is grateful for what they did for her, because if they had not come to break the Wall, she would never have woken from her nightmare.
Some time after retreating to Shiganshina District, Reiner and Bertholdt meet up with the Beast Titan. They try to convince him to help them rescue Annie, but the Titan refuses, and savagely beats Reiner after he tries to use his Armored Titan form to force him. As he is pulled from his Titan form by Bertholdt, the operator of the Beast Titan declares that they will wait to rescue Annie until after they have acquired the Founding Titan from Eren.
Reiner is seen alongside Bertholdt atop the Wall at Shiganshina District awaiting the Scouts arrival.
As one of the top ten graduates of the 104th Cadet Corps, Reiner is likely highly competent in the use of omni-directional mobility gear and respective weapons. He is also one of the best hand-to-hand fighters among the recruits, having also trained other skilled fighters such as Eren. Reiner is noted to possess both a strong body and will.
Reiner is able to transform into a 15 meter Titan referred to as the "Armored Titan" (鎧の巨人 Yoroi no Kyojin?) in the series. Reiner uses this form to break down the inner gate of Wall Maria and actively uses it after he reveals his identity and objective to Eren. The Armored Titan is capable of assuming human form at will, due to the intelligence it demonstrates in appearing to work with the Colossal Titan in breaching Wall Maria. As he retains his human intelligence, he uses his hand-to-hand combat skills against other human-turned-Titans such as Eren, which in conjunction with his armor-like skin, gives him a solid advantage in combat.
- Regeneration: Reiner, like all other Titans and humans with the Titan powers alike, has the ability to automatically regenerate any wounds sustained and even entire limbs. This also applies to his human form as seen when he sustained a broken arm in a scuffle against a Titan in Utgard Castle, his arm was almost fully healed when he rejoins the Survey Corps on top of Wall Rose. Furthermore, Reiner loses the bottom part of his forearm when it is sliced off by Mikasa, however, he is seen with a complete limb by the time he is in the Titan Forest a couple of hours later.
- Regeneration Withdrawal: Reiner possesses the ability to consciously control his regenerative ability, keeping it "off" to prevent injuries from blowing his cover as a Titan spy. He is the only one shown to be able to use this specific ability and notably in human form. Whether this extends to other regenerative abilities, such as the selective regeneration practiced by the Female Titan, is unknown.
- Enhanced Strength: During the massacre in the Shiganshina District, Reiner in his Titan form demonstrated enough physical power to raze the buildings around him by simply taking off into a charge, then promptly smash through the inner gate of Wall Maria. While squaring off in an attempt to capture Eren in his Titan form, Reiner was shown to easily overpower his opponent with punches powerful enough to blow at least half of his head off. Reiner’s tackle had enough force to throw Eren’s Titan form back into Wall Rose, cracking it in the process. In addition, he uses his unique hardened skin to supplement his physical blows making them deadlier than those of normal-based Titans. In his second fight with Eren, Reiner was easily able to barge out of Eren's assault and throw Eren's Titan form around without much effort.
- Enhanced Speed: During the battle in the Shiganshina District, Reiner in his Titan form demonstrates enough speed to successfully breach the district's inner gate. While fully armored his speed is noted to be much slower, however, Reiner has shown that he can choose to shed certain areas of his armor, such as joints located at the back of his legs, boosting his overall speed. This tactic was used several times by him successfully during his fight against Eren’s Titan form.
- Armor Hardening: While transforming into the Armored Titan, Reiner's body automatically produces a hardened, armor-like skin that covers most of his body, save for areas such as his joints at the back of his legs. The armor is hard enough to repel concentrated cannon fire without even stopping him, blows from other Titans such as Eren, as well as blade strikes from the omni-directional mobility gear. The durability of this armor is enough to withstand a direct collision from the Colossal Titan who fell from the top of Wall Rose, wounding most people in the area, incapacitating Eren's Titan form, and leaving a large crater in the ground. As stated previously, the Armored Titan can choose to harden or not to harden joints at will, sacrificing speed and combat ability for protection. However, this is his only remarkable weak spot: similar to a medieval armor, his body needs gaps around the joints in order to move with necessary speed. This makes him vulnerable in just a few spots, like the inner part of his knees and his elbows.
- Steam Generation: Reiner's Titan seems to overheat, judging by the "fire breath" that appeared after destroying the Inner Gate of Wall Maria. As his Titan bears solidified skin over most of its body, it seems that the excess heat and vapor build up and must be vented out through the mouth. The extent of this function the single time it appears was enough to superheat and ignite the steam that came out.
- Bertholdt Hoover - Bertholdt is his childhood friend and partner, working closely with him in their mission. They are rarely seen apart, with Reiner taking the lead most of the time. Reiner is also very protective of Bertholdt and he will follow his lead without question. Reiner is also shown to be aware of Bertholdt's affection for Annie, despite Bertholdt's claims, and encourages him to confess his feelings for her once their mission is complete. Bertholdt is shown to be greatly saddened by Reiner's duel-personalities and often has to remind him he is a Warrior and not a soldier, but still trusts him to lead their mission.
- Annie Leonhart - Annie has known Reiner since childhood. Despite being part of the same mission to exterminate humanity Annie is often very cold towards Reiner and generally seemed to avoid him, as other members of the 104th would note that Annie never seemed to interact with Reiner and Bertholdt. Annie's dislike towards Reiner likely spawns from resentment due to Marcel sacrificing his life to save him from Ymir's Titan. Despite this they were still able to work closely together during the battle of Trost and during the 57th expedition mission. When Armin revealed to Bertholdt and Reiner that the Scouts were aware of Annie's identity and claimed to be torturing her, Reiner appeared very distressed.
- Eren Jaeger - Eren was one of his closest friends, with Eren considering him both a "strong, capable guy" and something of a big brother. Eren looked up to Reiner, expressing that he wanted to become strong like him. When Eren was told that Reiner may have been an accomplice to Annie by Hange and Armin he was the most skeptical to believe it. When Reiner revealed his secret Eren was horrified but his sorrow quickly turned to anger towards him for betraying humanity.
- Armin Arlelt - Reiner has a close friendship with Armin, even risking his own scores to help the smaller boy during training. He is also shown to admire him for his intellect and quick thinking. When the Female Titan attacked, Reiner came to his rescue. After Reiner's identity as the Armored Titan is revealed Armin is highly saddened to learn of his friend's true nature.
- Jean Kirschtein - Reiner initially had a very low opinion of Jean likely due to his selfish desire to join the Military Police to live an easy life. During the battle of Trost, Reiner was surprised when Jean was the one who rallied the cadets. Even later during the 57 expedition mission before fighting the Female Titan he admitted to Jean he never expected him to be selfless enough to risk his life for others. Jean was highly saddened to learn Reiner's true identity.
- Sasha Braus - In A Sudden Visitor: The Torturous Curse of Adolescence, he is shown to work closely with Sasha and Conny during training and later, during her contest against Jean. When he expresses doubt and attempts to abandon their hunt for the Colossal Boar, she slaps and then elbows him. She shouts nonsense at him about his ancestors, and while he admits he does not quite get it he apologizes to her and rejoins the hunt. Sasha is later horrified to learn Reiner's true identity as the Armored Titan.
- Historia Reiss - It has been shown that Reiner has feelings for Historia and often contemplates his desire to marry her one day despite knowing that Ymir is in love with her too. However it is unclear whether or not it is his “warrior“ or “soldier“ personality that is in control during these thoughts as Bertholdt makes a remark on his change in character shortly after he thinks this. Though Reiner has acknowledged that she is important to their mission Reiner genuinely seems to have a desire to protect Historia from their mission. 
- Marco Bodt - For reasons unknown during the struggle for Trost, Reiner restrained Marco and left him to be eaten by a Titan as Bertholdt and Annie watched in tears. Reiner was quite traumatized to the point his persona split, becoming unaware of his own involvement in Marco's death. He did not remember this until after Bertholdt reminded him that he was a Warrior, as he appeared distressed over recalling the incident.
- Marco Bodt
- Numerous members of the Garrison Regiment
- Numerous counts of Wall Maria citizens
- Numerous members of the Scout Regiment
- Hajime Isayama has stated in recent interviews that Reiner is his favorite character in the series.
- When designing Reiner, Isayama took the eyes and eyebrows of David Beckham, as well as some characteristics from a personal friend of his, and added them to the appearance of Private First Class James Francis Ryan (Matt Damon) from Saving Private Ryan.
- Reiner's bulky body is not the result of his training from his time in the 104th Cadet Corps, but is inherited from his parents. Isayama likens Reiner's predestined body to Fedor Emlinenko, Koji Murofushi, and Hulk, people he believes to be naturally strong.
- According to Isayama, if the 104th Cadet Corps had an arm wrestling competition, Reiner would place second, losing only to Mikasa Ackermann.
- According to Isayama, amongst his fellow 104th squadmates, Reiner is the most popular boy.
- His name is Old Norse in origin, and means "Counseling Warrior."
- In German, the word "Braun" means "Brown."
- In Episode 2 of the anime, a young Reiner and Bertholdt are in the crowd when the food shortage is announced. This is an anime-only cameo.