|Frieda's Titan was superior to all other Titans. You could say her Titan had unsurpassable power.|
|— Rod Reiss claims the Founding Titan is the strongest Titan|
The Founding Titan (始祖の巨人 Shiso no Kyojin?) is one of the Nine Titans that was once in the possession of the Reiss family, who passed it down from generation to generation. Its screams can alter the minds of both humans and Titans, but in the case of the former, some bloodlines are exempt from its power. It is currently in the possession of Eren Jaeger, although Eren's lack of royal blood means the Titan is unusable in its current form.
The Founding Titan's power is used by screaming. Whoever has the Founding Titan does not have to transform in order to use its abilities, and the screams of a human would suffice. Furthermore, the screams do not have to be loud or even "screams": Frieda Reiss was able use the memory alteration ability by casually talking, although her target was only Historia who was right in front her.
By screaming, the Founding Titan grants its user the ability to control Titans at will and make them follow virtually any order. This was demonstrated by Eren Jaeger, who unintentionally commanded nearby Pure Titans to eat Dina Fritz's Titan and attack the Armored Titan. It appears to be only effective on Pure Titans, although those with the power of the Titans can still feel its influence. It was also used by the First Reiss King to build the Walls, commanding many Colossal Titans to harden their bodies and confine themselves into the resulting structures. In ancient times, Eldia used to use this ability to command an army of Titans for war; however, once set loose, these Titans became indiscriminate weapons of mass destruction that would slaughter Eldia's enemies. This ability has no known range, although the First Reiss King used it to command Colossal Titans that span across a large portion of Paradis Island. Rod Reiss claimed the power has the capacity to wipe out all the Titans, if used to its full potential.
The Founding Titan is able to modify the minds and memories of the Subjects of Ymir, even entire populations at once. This ability is related to the Titan control ability: As noted by Erwin Smith, Titans are simply transformed humans (specifically, the Subjects of Ymir); therefore, the screams that control the minds of the former should be able to affect the latter as well. It was used by the First King to make the Subjects of Ymir inside the Walls forget the history of the world before the Walls' installation. It was also used by Frieda Reiss to remove Historia's memories of her visits. Anyone who is not a Subject of Ymir is unaffected by this ability.
Only those with royal blood—the Fritz or Reiss royal families—are able to use the true power of the Founding Titan. However, if the Founding Titan is inherited by someone outside of the royal family, the power can still be used if the inheritor is in physical contact with a Titan with royal blood. This is demonstrated when Eren Jaeger temporarily used the Founder's power after striking the hand of Dina Fritz's Pure Titan.
If the inheritor touches a human of royal blood, although the full power of the Founding Titan is still locked, some snippets of the previous inheritors' memories can be realized. The touch of Historia Reiss and her father Rod occasionally resurfaced the memories of Grisha Jaeger. However, these memories are erratic and do not always come.
Vow renouncing war
Despite having the ability to control the Titans, no Founding Titan of royal blood after the Great Titan War expressed any desire to get rid of the Titans outside the Walls, even if the inheritor had expressed that desire previously. This is because these Founding Titans inherited the ideology of the First Reiss King along with his memories.
The vow "possesses" the King's successors and greatly changes their personality: They become compassionate, desire to create a "paradise" inside the Walls, and preach about peace and love among mankind.
The vow only applies to the royal family; therefore, the Founding Titan can still be used for war if it is inherited by someone outside of the royal family, and then that person touches a Titan of royal blood.
Nearly 2,000 years ago, Ymir Fritz gained the power of the Titans and became the first of all Titans, the Founding Titan. After holding her power for 13 years, Ymir died by unknown means, and her power was split between nine inheritors, each one having one of the Nine Titans. For the next 1,700 years, the Founding Titan presumably remained within her direct descendants in the royal Fritz family. The Eldian Empire, founded by the Nine Titans after Ymir's death, possessed a history of strife for control over the Titans between the various familial houses subservient to the royal family, but order was nonetheless maintained thanks to the Founding Titan.
After these seventeen centuries, the Founding Titan was inherited by the First Reiss King, the 145th Fritz King. King Fritz chose to abandon the conflicts of Eldia and relocated the capital of Eldia to Paradis Island where he used the Founding Titan to create many Colossal Titans in the building of three Walls: Maria, Rose, and Sina. In the absence of the Founding Titan, the Great Titan War continued. Over the course of the war, Eldia lost all its territory on the continental mainland to Marley and its people fled overseas to Paradis Island where they entered into the Walls.
Some time after the people were gathered within the Walls, King Fritz used the Founding Titan to erase the memories of the outside world from most of the population's minds, leading them to believe they were the last remnants of humanity in a world overrun by the Titans.
Upon the closing of the gates of Wall Maria, King Fritz announced to his relatives who chose to remain across the sea that a pact had been made with the Founding Titan. In order to secure peace for Eldia while simultaneously arranging for the nation's eventual destruction, King Fritz ensured that all successors after him would be overcome by his will if they chose to use the Founding Titan for Eldia's sake. Some time afterward, the King passed his power over to his descendants in the royal family, now known as the Reiss family.
For generations, the Reiss family passed the Founding Titan down from successor to successor. Eventually, the Founding Titan was inherited by Uri Reiss from his father. Early in his life with the Founder, Uri protected himself from Kenny Ackermann using his Titan, and he would later become a close friend of his would-be assassin.
Sometime later, in the year 842, Uri Reiss passed on the Founding Titan to his niece Frieda Reiss, daughter of his older brother Rod Reiss. Frieda presumably made little use of the Founding Titan for the next three years, though on occasion she visited her half-sister Historia Reiss and used the Founding Titan to erase her memories of each visit. When three years had passed, the fall of Wall Maria began. After hearing of the attack on Shiganshina District, the Reiss family gathered in the underground cavern beneath the chapel where the Founding Titan had been passed on for generations.
While in the cavern, they were visited by Grisha Jaeger, who had been tasked by Eren Kruger with taking the Founding Titan thirteen years ago. Grisha identified himself as an Eldian and a Subject of Ymir and begged for Frieda to use the Founding Titan to save the people of the Walls, but his pleas went unanswered. Seeing no choice but to fulfill his promise to Kruger, Grisha transformed into the Attack Titan and fought with Frieda's Founding Titan.
Due to her inexperience, Frieda was quickly overpowered and Grisha stole her power, killing Frieda before turning his attention to the Reiss family and wiping out their line, save for Rod who escaped with his life. Grisha returned to Wall Rose shortly afterward and searched for his family. He found his son Eren and adopted daughter Mikasa, but learned that his wife Carla had been killed. Grisha entrusted Kruger's mission to Eren, leading him into the woods alone and injecting him with a Titan serum. Eren would have no memory of the event for the next five years, and as a Pure Titan, he consumed his father, inheriting both the Attack Titan and the Founding Titan.
After the Fall of Wall Maria, Grisha Jaeger goes to the Underground Chapel where the Reiss family is and transforms into a Titan. Frieda Reiss also transforms and battles Grisha, but loses and is eaten. Grisha obtains the Founding Titan and then proceeds to kill every single member of the Reiss family, except Rod Reiss who escapes. He later finds his son Eren and injects him with an unknown serum, turning his son into a Pure Titan. Eren eats Grisha and inherits the Founding Titan.
Before fleeing the Scouts in the Forest of Giant Trees, Reiner states that the connections between the Reiss family and the Order of the Walls make Historia Reiss a valuable asset for the Warriors' mission, and having her with them will make their goal much easier if Eren Jaeger is not the "Coordinate" they are searching for.
Later that day, the Warriors' suspicions are confirmed when Eren unleashes the Founding Titan, striking the hand of a smiling Titan, screams, and causing all the surrounding Titans to swarm it and tear it to pieces. When Reiner and Bertholdt approach him afterward, Eren's outburst towards them once again triggers the Founding Titan and sends the nearby Titans rushing towards the Warriors, allowing for the Scouts to escape. On the journey back to Wall Rose, all Titans previously encountered ignore the Scouts and instead run in the Warriors' direction under Eren's subconscious orders.
A squadron from the Military Police led by Kenny Ackermann kidnaps Eren Jaeger and Historia Reiss and brings them to Historia's father, Rod Reiss. After reading a note from Eren on how Ymir got her Titan powers, Hange Zoë theorizes that the government is planning to devour Eren to gain his power.
Eren awakes, chained up and gagged, in the Reiss family's Underground Chapel, the location where the power has been passed down for generations. As he slowly wakes up, he has a vision of Frieda Reiss, a former Founding Titan, bushing her hair.
Later, Rod and Historia Reiss touch Eren's back, triggering a chain of memories: Eren unlocks memories of his father, fighting Frieda and eating her (inheriting the Founding Titan), slaughtering the Reiss family, and then feeding himself to Eren. Historia unlocks memories of Frieda who once used the Founding Titan's power to erase herself from Historia's memories.
Two months later, the Scout Regiment reclaim Shiganshina District. They come to the Jaeger family's basement where Grisha had kept his secrets for Eren. In one of three journals hidden within the basement, they read Grisha's story of his childhood and when he learned the nature of the Founding Titan. In Grisha's past, he had joined a group of Restorationists who desired to take the Founding Titan from the king of the Walls in order to restore Eldia to glory. The organization failed and Grisha alone was given the task of taking the Founding Titan by Eren Kruger, an Eldian spy in the government of Marley.
When the military of the Walls gathers to discuss the discoveries from the basement, Eren thinks back to the time when the Founding Titan came forth in the presence of the Titan that ate his mother. Recalling his father's memories of his first wife, Dina, Eren realizes that Dina's Titan was responsible for the presence of the Founding Titan. However, Eren decides against revealing his discovery to the military, fearing that the idea of turning a royal into a Titan for Eren to come into contact with may put Historia Reiss' life at risk.
- The Founding Titan is the only one of the Nine Titans that have a bloodline restriction, as only royals can freely use its abilities.
- Eldian artwork has on several occasions depicted the Founding Titan with a war horn. This may be an artistic representation of the "scream" that activates the Founding Titan's power.
- Frieda Reiss normally had blue eyes, but when she transformed into an Intelligent Titan, her eyes glowed purple. When Grisha Jaeger devoured her and obtained the Founding Titan, his normally green eyes turned purple as well.
- The Founding Titan's power is extremely similar to the Beast Titan's ability to control Titans, which he also uses by screaming or talking.
- The songs Guren no Zahyou and ERENthe標 both reference the Coordinate in their titles, and Guren no Zahyou also mentions it in its lyrics.
- When members of the Reiss or Fritz family inherit the Founding Titan, they are affected by the First Reiss King's will, and at times, their normally light-colored eyes emit a purple glow.