Why wouldn’t Voteil take his mother’s name as his last name since he didn’t have a good relationship with his father? Was he simply not old enough to make the decision or realize he can do that?

Kurogh had more of a name for himself than Feuriah did. He was a celebrated Warlord, one of the best Kurosia had to offer, so Voteil taking his name made more ‘sense’ whereas Feuriah was adopted into Kurosia, and merely served as a military soldier/guard before she fought to be Queen. In time, I think Voteil would have taken on his mother’s name eventually, though with him being a Seuth everyone knew who he was and wouldn’t really look or consider his last name as being important. In time, he’d be more important than both his parents, if Malefor hadn’t been involved.

~Weird Hyenas