Just novels, please, not movies/tv shows/comics/manga or books based on them.
Watching the latest episode of Supernatural with a “good” demon (Ruby) reminds me of Spike and Angel on BTVS/Angel in as much as she’s trying to walk the straight and narrow too, and has turned on evil. I tried to think of a novel with a demon who fights on the side of good, or even just lives a straight life now without harming anyone, but I couldn’t. Just TV shows and so on. The vampire who is (now) good - Bill, Ivy, Promise, Louis etc - is an easier find in novels, it seems.
There have to be novels with demons who have reformed themselves, though, don’t there?
How about Crowley from Good Omens? He doesn’t exactly ‘live a straight life now without harming anyone’, but he decides that bringing on the Apocalypse maybe isn’t such a good thing and joins with the angel Aziraphale, who has come to the same conclusion. (Actually, they’ve been rather friendly with each other over the millennia. Aziraphale tells Crowley that he’d always thought there was a spark of goodness in him, and Crowley tells Aziraphale that the angel is enough of a bastard to be worth liking.)
I thought that in the Myth books demon was a nickname for a dimensional traveler. So Skeeve (a human) is a demon, and so is pretty much every character in those books.
There definitely are, but as to whether they’re worth reading? Ehhh.
Working for the Devil by Lilith Saintcrow (I hope that’s not her real name) has a reformed demon character. It ends kinda cliffhangery (and I stopped at the first book) so I’m not guaranteeing the reformed part.
I had other books in mind and now I’ve forgotten them. I’ll come back if they do.
I’m not positive, but I think Teddy London deals with, at least, some ambivalent demons. Don’t know if they are reformed…
Regardless, worth a read. A great series… gritty Philip Marlowe noir meets Lovecraft. I swear these novels are one of Joss Whedon’s biggest unacknowledged literary influences.
Night’s Master by Tanith Lee. Azhrarn definitely is not “good”, and he’s certainly not “reformed” either – but he is also just as definitely the protagonist you’ll like and identify with.
Delerium’s Mistress is a later book in the series, and it’s protagonist, Azhriaz (daughter of Azhrarn) is could be described as both “good” and “reformed”.
Also, they’re quite good books, even though I see they’ve foolishly been let fall out of print.
I Lucifer by Glen Duncan (which I am currently reading and haven’t quite finished yet) has the devil (Lucifer) offered a shot at redemption by heaven provided he can inhabit a mortal body for a month without commiting a deadly sin.
It’s funny and narrated by Lucifer himself. Worth a read, although it’s a fair guess he never really fully gets redeemed.
At least one of Piers Anthony’s Xanth novels features a reformed demon. I recall this fact because the character was a woman who was clearly described as desirable, yet was also clearly above legal age.
I’d mention Planescape: Torment, except that it’s a computer game, not a book.
(Well, there is a book, but it’s almost completely unlike the game, so it doesn’t count.)
In the game, one of the characters who can join your party is Fall-From-Grace, a reformed succubus who runs the Brothel for Slaking Intellectual Lusts. In other words, it’s a place filled with beautiful, scantily-clad women whom you can pay to… play chess.
“Oh, so Mistress High-and-Mighty’ll be joinin’ us? What do we need her for?”
“You couldn’t possibly understand.”
Mike Carey has two books about private eye/exorcist Felix Castor, and he has a sidekick (sort of in that she hasn’t killed him yet) named Juliet who is a sucubus. She’s not so much reformed as on hiatus. The first book - The Devil You Know -was pretty good. The second - Vicious Circle - was excellent.
Hex and the City has Pretty Poison, a succubus who fights on the side of good because Sinner, the man she was sent to corrupt asks it of her. She truly reforms in the end.
Personal Demon by L Sprague DeCamp.
The Second Summoning involves a demon accidentally summoned in the form of a teenage girl, who is contaminated by the humanity of her form and gradually reforms.
I haven’t finished reading it, yet, but Wayne Barlowe’s God’s Demon seems to qualify. (Reading the author’s art books Barlowe’s Inferno and Brushfire first would help, though—really give you an idea of what the setting looks like.)