I just finished reading K-PAX and I'm looking for a noun to describe the main character prot, a compassionate being who helps people work through their issues. Idiomatically I might say prot leaves things better than he found them.
One word that came to mind is do-gooder, but this unfortunately has an informal, derogatory meaning.
A good opposite for my word is trouble-maker, someone who intentionally (and possibly habitually) stirs up trouble. So I also looked at peacemaker; the definitions I found, though, tend to relate this word more to settling interpersonal conflicts than personal, which is prot's specialty.
Words like humanitarian, philanthropist, and altruist capture the character's desired end-result well but have a more missional tone than what I'm looking for. Although prot was summoned here to help a specific man in need, his kindnesses to others appear secondary (like a hobby, almost) to his goals of researching Earth or waiting for a viable time to return to his home planet.
Is there a better word to describe what I see in prot?