Well, in a very short summary - the MC wants to forget about his brother and his shitty situation, and the Mal offers him just that (a escape from reality). And basically, they both want to die together. The ML because he “loves” the MC, and the MC, because the ML has told him that he can do whatever he wants with him, so he wants to kill him, but knows that keeping him alive is the best way of “revenge”.
Also, they are both sad and lonely af, so they technically want to die, but at the same time stay together. Hope that makes sense!

I’ve said this a couple of times, but I don’t think the manhwa truly does justice to the novel. It’s still full of rape and wtf moments, but you guys would understand why he suddenly calls him babe and is “enjoying” it. So if you ever can, I do recommend reading the novel, just remember it’s still not romance