Spark could be leader. Despite being a selfish bitch she has experience with organized crime but I think Vlad would probably have to give her the responsibility since everyone hates her. Not only that but she understands that her position in the program relies wholly on Vlad's approval. If he says she's responsible for the team then she'll take care of them accordingly, she won't be nice about it but she won't be reckless or unfair with them.