That was basically the best episode. It was the first one that Nikola was introduced in, he had been in some of the older clips that were played when John Druit and Helen Magnus were talking about when they all injected themselves with the ancient blood, but that was when he still had the mustache ^^
I like when he gets done with his test in the underground city, and he looks up at helen and she looks worried for him, and he says something like "HA, admit it, you felt genuine concern for me!" And my other fav quote from him is "Kiss me and I'll save your life" from the five. I hope that he becomes a regular on the show.