Non-cliche slavery in fantasy campaign settings?

[Celebrim]

Well, you don't know what else might have transpired had Pettigrew been killed. I'd say, to follow fantasy tropes, the dark blot on their souls would have let to equal or worse evil. Remember, Harry's mercy was instrumental in defeating the dark lord. With a darkened heart, would Harry been as likely to a similar act of mercy?

Maybe. It's easy to say that in hindsight when everything works out in the end. It depends on whether you consider killing a mass murder who is responsible for the deaths of your parents and who may kill again an act of evil likely to stain one, or rather the rough work that must be done to defend ones loved ones from evil and not staining at all. Standard children's story tropes answer one way. I'm not entirely convinced things worked out better given the deaths of Peter is ultimately responsible for, or that the author gives Harry enough motivation beyond the need to not have the story's rising action be put on hold at the end of book three. Harry certainly is never made to say or think that Peter doesn't deserve death, nor does the author claim Peter doesn't deserve death. Harry just seems willing to let something else get their hands dirty in his place - which is not virtue. Arguably, Harry doesn't kill Pettigrew only because he has at that time a naïve faith in authority - naivety that's going to be driven out of him the hard way in the long run. Point being, I don't think there isn't an easy answer here, and the author never has Harry wrestle with it.

On other notions: Tolkien, while depicting a detailed and realistic world, might be faulted for portraying Orcs as corrupted, and, based on the absence of the contrary in the stories, irredemable. In LOTR, Orcs are simply to be slaughtered, the same as mad dogs must be put down. Being corrupted fits a fantasy story, but can be hardly be seen as presenting moral depth.

That depends on what you are looking for. If you wish to have the orcs represent some human minority, then sure their point in the story is ugly racism and so forth. But, we don't need to have the orcs represent humanity at all. There are plenty of actual human peoples in the story - Southrons, Easterlings, the Wild People under Saruman, the Pukel men, etc. If you wish to build a case for racism or lack of a moral depth in race relations, you can turn there if you like - though Tolkien has already addressed that particular critic within the story itself. But if you admit it is fantasy, why can't orcs represent the baser parts of our nature, so that in slaying orcs is a metaphor for rejecting our evil selves? If they are truly irredeemable, why assume they are metaphors for humanity at all? Why not assume they are metaphors for corruption itself? After all, when orc is used as an adjective, that's what it is used to describe, and ring brings out the 'orc' side of everything around it - including Boromir and Frodo. And considering the metaphor thusly, what does it say about Denethor - who refuses to confront the orcs but hides himself away in a lonely tower with his own dark thoughts, compared to Théoden - who comes out of his gloom in order to face them? Conversely, we see why fighting orcs with the power of the ring - becoming an orc to face orcs - is impossible. Tolkien wouldn't need orcs to demonize humanity. You can demonize humanity plenty without inventing orcs. You need orcs only if you want something inhuman.

And: Slavery involves a lot worse than many many folks imagine.

Granted. Even Roman house slavery is a pretty nasty business.