The Human Bearer (BL, Aliens, Mpreg)

A male human becomes the bearer for a snakeman's egg.

Born in the slums of Earth, Riordan has never thought of looking at the stars. He doesn't believe in destiny, either, unless it's the one he's making with his own two hands. An Earth conquered by aliens, a species that is half human, half snake called Xenos, becomes even an unbearable destiny.
So he changes it. The snakemen didn't force Earth to bend the knee for no reason. They don't care about Earth's resources, except for one. Males in their early twenties, beautiful and strong enough to carry the aliens' eggs.
A species made up of almost only males, Xenos cannot reproduce in other ways. They conquer planets because they need to find bearers for their eggs. Earth appears the most promising of all the worlds they've conquered so far. Male human bodies are strong, resilient, and it doesn't hurt that they're so physically attractive, either.
Earth must pay tribute, but there's no need for forcing young men to become bearers. They come in throngs, seduced by the promise of a new world and a life beyond the stars. Riordan joins their numbers, although he's not blond and beautiful like them.
But he gets chosen, and his surprise turns sour when he understands that his owner, Xana Lei, is a male. Somehow, lost in translation between the two species, he believed he would end up carrying a female's egg.