Sae Alpha Adeul, Heon Omega Abeoji

When Eunwoo marries his alpha coworker, Taejoon, he's ready for his own happily ever after. But all that changes when, one day, Taejoon brings home Joowon, his son from his former omega partner. Though Eunwoo accepts and raises Joowon as his child, the marriage takes a turn, and after the divorce, Joowon is sent abroad. Ten years later, Joowon shows up, claiming he one-sidedly imprinted on Eunwoo!