While I wasn’t a big fan on his persoanlity, he was a decent character. While I didn’t really see much of his backstory during my route of the game, he is the half-brother of Mercedes. After some family drama, he loses much memory of his original self and joins Edelgard’s side.
Becoming the Death Knight. I faced him in a few missions and he was super strong. But he’d always flee before any real damage would fall upon him.
Eventually he became part of my party. He was super-strong though his horse wasn’t as mobile as I’d would have liked.
But after Byleth and Edelgard, he was my strongest character on offense and defense. I would have lost the final battle against Rhea without his help.