Berith is a prince of Hell, just under Lucifer himself, which means he has enemies, and a lot of them. Usually, Berith solves that problem with torture and death, but that's not always a possibility, like when he's gifted a human by a demon who wants to see him torn off his throne. The only thing he can do is bond the human to him so he doesn't die. But then what?
Mel has no idea how he ended up in Hell or how he'll go home. The only thing he knows is that Hell is no place for a human, even when that human is bonded to a prince of Hell like he is—or maybe especially so. He's being used as a chess piece, and he doesn't like it, but what can he do when his new owner doesn't allow him to go home?
Mel has to learn to live in Hell, while Berith has to understand how to deal with a terrified but stubborn human. As they spend time together, they both see that maybe things will work out, but they're still in Hell, where everyone wants everyone dead. But maybe Mel can bring a little of his humanity to Hell, change how things work, and show demons they don't have to torture their way through life.
That is, if he survives long enough.