Morita

Just a little lad

Majorly depressed human man gets possessed by alien parasite, said parasite somehow manages to help with its human hosts's mental health problems
For the most part Morita is in control, and the parasite only rlly takes the wheel from him when he refuses to go outside or get out of bed.

Sometimes it speaks on his behalf too. He doesn't like it because the parasite has a completely different, more aggressive and loud personality, but it does help a bit.

Morita curbs the parasite's hunger for flesh by feeding it shrimp crackers. No matter what it eats nothing affects the human host. Good thing too bc now all it wants is junk food.