Reiner Braun started out as a brotherly figure to many in the 104th Training Corps of Attack on Titan, including Eren. However, when revealed to be the holder of the Armored Titan responsible for the breach of Wall Maria, he grew to be universally reviled among the Scouts. Driven nigh on insane by the guilt he held on to for his actions in the Marleyan operation to retake the Founding Titan from Paradis, Reiner was unable to reconcile his sense of duty with his ideals. His defeat at Shiganshina cemented this, where the sacrifices he made all proved to be in vain. The intense mental strain of this caused him to develop Dissociative Identity Disorder, where one part of him was a Marleyan Warrior, and the other was a soldier staunchly devoted to Paradis and its cause.