Yeah, he is definitely
Ramsay Bolton, the Bastard of Bolton.
I liked the little hint also when he told Theon 'That would be quite the hunt' when talking about the Stark boys, because part of his whole thing was live hunts followed by torture, rape, and dismemberment, which Roose 'tolerated' and 'chided' him for but never really cared about. His comment is a little more twisted when you realize he's not interested in hunting them simply to find them.
Also, the Bolton's sigil
