His Siren Prince

Crown Prince Azul of the Siren Kingdom must continue the bloodline if his people are to survive. He has slept with every species on the continent, except for a human.
General Carrion of the Sun Nation is one of the few humans left alive. When he returns from battle, he lays eyes on the siren prince again, and knows he must have him.
Azul needs a father for his children, and Carrion is more than happy to provide. Especially when the mating bond ignites for them both, and passion sweeps them away in one fervent night.

TROPES:
Age Gap, Royalty x Military, Fated Mates, Mpreg, Instalove & lust