Jean Kirstein is a main character in Attack on Titan who begins as a trainee in the Survey Corps. Initially motivated by the prospect of a comfortable life in the Military Police, Jean gradually transforms into a dedicated soldier. He is known for his pragmatic and often sarcastic personality, frequently questioning dangerous strategies. Despite his initial reluctance and self-preservation instincts, Jean demonstrates genuine courage and loyalty to his comrades, particularly Eren and Mikasa. He becomes an accomplished Titan fighter and plays a crucial role in humanity's battles against Titans. Jean's character arc shows significant growth from a self-interested recruit to a committed soldier willing to sacrifice for humanity's survival. His realistic perspective and dry humor make him a relatable character who often voices the concerns of ordinary soldiers.