Prince and Betrothed by Tavia Lark

Being claimed shouldn’t feel so lonely.
Sei’s power isn’t truly his. As a grail, his role is to serve a mage by augmenting their magic. He’s equally nervous and excited about his arranged betrothal. After a life without intimacy, Sei will finally fulfill his true purpose as a treasured, valuable grail.
There’s only one problem: Sei’s new betrothed is the legendary Marek Dire.
The dragonrider prince is powerful, intimidating, and larger than life—or at least larger than Sei. Prince Marek doesn’t want a husband, especially one like this. Sei might be captivating, but he’s also too delicate and obedient. Marek vows to break the betrothal, and he refuses to use Sei as a grail.
No matter how much Sei wants to be used.
But Marek underestimates Sei. Wielding kindness as a weapon, Sei discovers unexpected tenderness in Marek—and new fierceness in himself. But being a grail in power-hungry Draskora is dangerous, and Marek still fears two things. That someone else might hurt Sei…
…or that Marek himself will.