What they have is nameless and imperfect. It is nameless because they are unsure of what to call it, as the usual terms don't seem to fit. A relationship it is not, since there's hate (swords and wounds and submission), but neither is it a friendship, since there's love (caresses and kisses and longing). It is made imperfect by the fact that they both love and hate themselves for the things they have done, and for what they are now doing.
It is a volatile mix, and he isn't sure how it is kept from exploding. The only certainty is that the intensity born of their mutual self-loathing and desire for one another is what keeps them from separating and never rejoining. They have grown too accustomed to their peculiar situation, rife as it is with tension and the need for release.
He knows that out of all of them they are the least deserving of happiness, but when he takes the older man to bed (silently pleased at how the wizard responds to his touch), he finds he doesn't care. And he knows, too, that when the other gives him head in the dead of night (sharp prickpoints grazing his length), that the enjoyment is not one-sided.
Left to themselves, they're broken pieces of a scattered puzzle, unwanted and unneeded by preoccupied players. But once connected, they meld and fill the gaps.