I'm wondering if anyone has a copy of this story - it was on LJ and it's called Bargaining Chip, by Mercury Alice. I don't have access to it. This was the summary:

War looms as a distant danger on the borders of Anglica. To ensure the kingdoms safety, Lord Zachariah arranges an alliance with a tribal clan known for their unbeatable prowess in battle. Their leader, Dean, can be a hard man to win over - luckily Zachariah’s already thought of the perfect bargaining chip: his sheltered young nephew, Castiel.

Thanks!