Sebastian was born in Romania and moved to the US with his mother. Though he has been in quite a lot, such as Gossip Girl, The Covenant, Kings, Black Swan, Political Animals. He won the hearts of many more fans and adoring viewers in Once Upon A Time.
As he said, "he's known all along before everybody else that this was going to happen, so this is not a big surprise to him. From where he comes from it's like, 'Oh good. Now everybody is going to see what I've been talking about over and over again, but no one was listening to me.'"