What's Wrong with Reiner?
During the First Season and the First Half of the Second Season, Reiner Almost Never Truly Acted Like His True Self. His Acting as a "Big Brother" to His Team...
During the first season and the first half of the second season, Reiner almost never truly acted like his true self. His acting as a "big brother" to his team was nothing but an imitation of his deceased friend Marcel Galliard, making him suffer from a multiple personality disorder, which is now cured.
What mental illness does Reiner have?
Yeah, Reiner seems to suffer from a case of Dissociative Identity Disorder (DID) which he creates an alternate personality, maybe to save himself. Well, I honestly think that he is always a true warrior inside and only suffers from DID because he has to act as a soldier while being a warrior back then.
Is Reiner a villain?
Reiner Braun is the secondary antagonist of Attack on Titan. ... After his true identity is revealed, he serves as a major antagonist and foil to Eren Yeager. Reiner becomes the protagonist of the Marley arc and serves as Warrior vice commander, behind Zeke Yeager before the latter's defection.