Carapaces are chess pieces made through some kind of weird cloning. They live on the moons and battle each other under the direction of their King and Queen. We saw the cloning labs on the meteors, John and Karkat both used one for ectobiology.
Imps are a subset of underlings; the cyclops(?) Rose blinded in the beginning is another. The Hero defeats them for grist and to level up. They work under the Denizen, who makes them as part of the deal they made with Derse to help fuck up the Lands.
Well, yes, but all are Game constructs 🙂 What interests me is the morality of it and what that implies about the level of personhood and realness quotient each has. By Game logic killing imps and ogres must be ok because you’re rewarded for it with grist – and also because they’re attacking you. Even though imps, like carapaces and consorts, are people, or behave like people, in cowering from ogres with John, getting high with Gamzee, watching movies with Jade and John. Because they’re not attacking any more, apparently, does that make it no longer ok to kill them? Or would killing an imp on the Party Boat for the grist haul be an act with zero moral consequences because they were designed as Game enemies?
Mostly, though, I just like imps, I think they’re endearing as hell and I want more scenes where they get to watch movies and less where they get hit with hammers.