The Braun family (ブラウン家 Buraun-ke?) is an Eldian family residing within Liberio. Reiner Braun, the inheritor of the Armored Titan, hails from this family, as well as Gabi Braun who is likely to inherit the Armored Titan.
At some point, Karina met a Marleyan man and later gave birth to Reiner. However, unions between Marleyans and Eldians are forbidden, so she had to remain in the internment zone with her son. Karina later revealed his origins to him and wished they were born Marleyans.
This led Reiner to become a Warrior cadet with the goal to gain one of the Nine Titans and make his mother and himself honorary Marleyans. He succeeded in becoming a Warrior, was praised for his loyalty, and inherited the Armored Titan in 843. Two years later, he took part in the Paradis Island Operation and infiltrated the Walls.
Sometime later, Gabi followed her cousin's footsteps and joined the Warriors. Her achievements allowed her to become a serious candidate for the inheritance of the Armored Titan.
As the Marley Mid-East War is coming to an end, the Marleyan army is fighting at Fort Slava. Gabi finds an opportunity to prove she deserves to become the next Armored Titan, and manages to blow up an armored train, which allows the Jaw Titan to penetrate their enemy's defenses. As the Armored Titan, Reiner joins the battle and proceed to kill the remaining soldiers.
At the end of the war, Reiner and Gabi go back to Liberio where their relatives are waiting for them. The whole family has dinner and listen to Gabi telling them about the Fort Slava battle. Her parents express their pride and when Karina asks about Gabi's chances to inherit the Armored Titan, Reiner assures them she will definitely have it. Karina expresses joy at the idea of having two Warriors in the family, then complains about the islanders' existence, which leads the family to ask Reiner about his time in Paradis Island.
However, Reiner has misgivings about becoming a Warrior and he later tries to take his own life. He stops himself when he overhears Falco Grice's frustration over trying to beat Gabi, and realizes that he still cares about the Warrior candidates. After attending a strategy meeting, Reiner and the other Warriors watch the candidates train and Falco manages to overtake Gabi for the first time. Though the other candidates are congratulatory, Gabi hits Falco and tells him that he is not the same level as her and her contributions to their country. Falco reveals that he is not doing this for their country, but for her, but Gabi is unable to understand what he means by that.
After Falco runs away, Gabi checks out the festival being set up in Liberio. She is positive the internment zone was chosen to show the rest of the world that Eldians do not need to be feared. Her friends come get her the day of the festival and the four of them stuff themselves with food, mostly paid for by her cousin, Reiner. He calls her a glutton after she eats so much she becomes sick.
The evening of the festival, Reiner is called away from the other Warriors by Falco, who leads him to a disguised Eren Yeager. Eren's transformation into the Attack Titan collapses the building around them, incapacitating Reiner for most of the battle that follows.. However, Reiner manages to muster a partial transformation into the Armored Titan that allows him just enough strength to save the Jaw Titan from extermination.
Meanwhile, Gabi tries to fight the members of the Survey Corps who have invaded Liberio. As she sees them retreating, she chases after them and manages to shoot one in the head while his vertical maneuvering equipment is still attached to the Survey Corps' airship. Realizing that she will likely not survive going up to the airship, she asks Falco to tell her family that she fought to the end.