Reiner Braun's backstory is one of the most heartbreaking twists in 'Attack on Titan'. At first, he seems like this loyal, dependable soldier—big brother energy personified. Then boom, we learn he's actually a Warrior from Marley, sent to destroy Paradis. The guy's been living a double life since he was a kid, and the psychological toll is brutal. Imagine carrying that guilt while also being brainwashed to believe your victims are devils. His breakdown in the forest when he confesses to Eren? Chills. What gets me is how his trauma manifests—dissociating into 'soldier' and 'warrior' personas, clinging to this idea of being a hero while drowning in shame. The way Isayama writes his mental unraveling is masterful; it makes you hate him, pity him, and somehow still root for him.
And let's not forget his relationship with Marcel, Bertolt, and Annie. Marcel's death haunts him, and his bond with Bertolt is this tragic codependency where they're each other's last tether to humanity. Even his dynamic with Eren shifts from mentorship to mutual hatred to... whatever that pathetically sincere 'I think I'll stick with you till the end' was. Reiner's whole arc is about the cost of indoctrination and the impossibility of atonement. Dude even tries to off himself multiple times. Heavy stuff for a 'shonen' series.