Title: The Lord's Bride
Shion is part of a powerful family, but as a branching cadet family with no blood ties to the main family, he gets all the ire from all the other branches, but without the power the main family has. The main reason for all of the ire? It's due to a long-held tradition between his bloodline and the head of the main family. Their ancestors were once in love but could not be together due to their differing classes. Unwilling to be without each other, the ancestors performed a bonding ceremony, rebelling against their families and solidifying their love for one another.
Now that Ao, Shion's former childhood friend, has obtained the role of head of the main family, he fully intends to carry on the tradition of binding their two families together through this bonding ceremony. Unfortunately, this needless tradition has caused immense fury amongst all of the other family members, all of it directed toward Shion, who doesn't have the power Ao does to defend himself. Shion never wanted to go along with this stupid tradition and, as such, fully intends to escape as soon as he gets the chance. Ao, though, has no intention of letting Shion go.
On the surface, it may seem that Ao is just going along with all of this for the sake of tradition, but there are much deeper reasons that even Shion can't fathom.