Ruined By His Alpha King by Lilo Quie

Stamel
Fifteen years ago he stood in a glade and watched a nymph playing with the love of his life. On that day, he traded things he cannot remember, with a promise that one day he would be king, even if not of his own country. Since then, it’s been one mission from the goddess after another and a myriad of betrayals trying to set the perfect stage to make a certain beta prince all his own.

Seidrik
Seidrik has used his brother as a shield from Alluin’s wrath his entire life, and now that Virion and Saria have found their mates, he finds himself subject to his father’s ire. The goddesses have declared his weakness, have told the world he will not sire an heir. He is useless to the crown in all but clerical ways. There’s just one problem, aside from his narcissistic father—A certain alpha prince. Prince Stamel has been blackmailing him for his secrets since they were small children. Back then, he only wanted simple things, a kiss, a promise. Now that Seidrik must take Stamel back to Liaberos with him, it’s clear that the alpha will stop at nothing to have him as his mate.