We can work out most the details later but this is the general plot.
Two kingdoms (A and B) waged war for many years, both sided winning and losing battles equally. Eventually however one of the kingdoms surrendered eventually.
One of the infamous generals of the victorious side gained fame in the war.
Unfortunately for the other kingdom (B) it involved a lot of their people dying, so though the war is over some people attribute their loss by focusing their hatred/anger/frustration on him.
Kingdom (A), after the war learns the atrocities the general committed against the other Kingdom. They find his ways to be too bloody, with no emotion or remorse (For now these are the general rumor , the actual guy could be whatever) and perhaps they may be frightened oh him.
Since he hasn’t committed treason or a crime , they send him to Kingdom B as a sign of good faith (Hah!).
He is to be the king’s royal bodyguard. The king however has no need for him and gives him to his daughter. (Maybe she’s secretly powerful too or innocent/scared ...anything you would prefer)
He is (semi) hated, feared and his name reminds people of their defeat to Kingdom A.
There might be a bit of everything (action, romance, angst etc)