The Royal Alphas (Books 1-3): - The Royal Alphas Collection, #1

This collection includes the first three books in The Royal Alphas Series: THE SELKIE PRINCE'S FATED MATE (book 1):A Selkie prince forced to produce an heir. An omega destined to become a royal's fated mate... Prince Kai's life as he knows it is now over. As the firstborn alpha to the Selkie King of the North, he's required to produce an heir. Whether he wants to or not. When the Selkie Seekers finally present his fated mate, he dreads being tied to this stranger for the rest of his life.
He can only hope his omega will be easy on the eyes and somewhat intelligent. THE SELKIE PRINCE & HIS OMEGA GUARD (book 2):An alpha prince ready to find his fated mate. A Selkie who wishes he wasn't omega-born... Unlike his brothers, Prince Adrian, the dutiful second-born son to the King of the North, looks forward to finding his true mate and producing an heir. Until he stumbles across a beta guard with an enticing scent. THE SELKIE PRINCE'S UNEXPECTED OMEGA (book 3)An alpha claim.
A possible heir. A Selkie prince whose mistake might just be what the fates intended. Zale, the third alpha-born son of King Solomon, is concerned. His youngest brother, Caol, has been spending time with an unbonded omega. Being a responsible alpha, Zale feels it's his duty to warn the omega Finn before he and Caol get into trouble. Especially since Finn had only been brought to the colony by their father in case his oldest brother's fated mate couldn't conceive.
However, when Zale goes to Finn's quarters to have a word with him, he isn't expecting to discover what he does: the omega in the throes of oestrus and begging for an alpha's assistance. Note: This collection includes m/m shifter mpreg stories. Due to the "knotty" times in these books, they're recommended for mature readers only. While they can be read as standalones, it's recommended to read the series in order.
And, like all of my books, each has an HEA.