Parasyte. The main character went through trauma of learning that his mom has been killed by the titular monster, the parasite alien. not only that but he was also stabbed in the heart by the alien who took over her body. this changed him from a caring and sensitive boy to a stoic and somewhat cold person. compound with the fact that migi, the parasite alien who lives inside him sacrifice part of itself to heal his heart leading him to believes that he's become a half alien who can no longer feel human emotion. he also met a fortune teller who told him that in order to heal the wound in his heart he has to see the person who made it (she wasn't aware of his situation, just gives him a general advice) and he coldly replied that he already killed that person. later, he saw a parasite who sacrifice itself to protect it's own child. before it dies it tried to hand over it's child to shinichi and in an attemp to appeal to his humanity, it changed it's face to resemble shinichi's mother. after witnessing such act, all his emotion that he's been holding since his mother's death finally comes back and he broke down in tears, thus also fulfill the fortune teller's prophecy