The only fiction I know that features a stuttering character who is a good person, and the book/movie isn't about overcoming the stutter (like "The King's Speech"), is a Russian book and movie series about a detective named Erast Fandorin. It's a high-quality historical series, and the protagonist has a stutter which is not portrayed as a flaw, he lives an interesting and fulfilling life :) I really enjoyed reading it, in general, not because of a stuttering character, but it was nice to finally read about one who isn't flawed, evil, cowardly, or gets rid of it in the end.