Soul Fire - Realm Walker, #3.5

Goaded by her common hybrid roommate, Halsey, the princess of the fae realm must meet the challenge. Terra can't get the best of her. To prove she's more than royalty, she finds the inner courage to embark on a mission in search of a fabled ancient grimoire containing the most powerful spell of all time. She enlists Bjorn, an infuriating sky fae, to assist her. It isn't that she likes him or even tolerates him.
She needs the help and there's no one else to ask. He can't stand her entitled royal highness anymore than she can stand him. They must find a way to work as a team, or the grimoire will remain elusive. Sparks between them flare as they begin the journey and drudgingly try to find common ground in their adventure in Navarin, the realm of the fae.