>>108365599Man-Thing was a guy that fell face first into an interdimensional nexus while melting from radical chemicals. It ended up merging him with the swamp and giving him superpowers, but totally destroyed his personality and rendered him into a mute, mindless empathetic creature that roams the swamps. It can sense emotions and that's usually how it finds people to help, but when he feels fear it makes him mad and start to seep out a highly corrosive chemical from his body, hence the tagline "Those who know fear burn at its touch".
Stories about Man-Thing are similar to a story about a random animal or monster, which he pretty much is, out in the wild that sometimes does good deeds and is often misunderstood but the world outside its home.