Season 1 generally

Corrected entry: The fact that Nina was a double agent brings up a lot of inconsistencies. Like why would she pressure Jack about the keycard if she was in on it with Gaines? And Why did she reveal Jamey as the dirty agent if she recruited her in the first place? Also why did Gaines order Jack to kill Nina if if they were working together?

Correction: I don't think Nina was involved with Gaines, or at least, Gaines didn't have any knowledge of Nina's involvement with Drazen. I think Nina would only be called upon if Drazen thought it was necessary. He probably made it clear to Nina to act as she would normally, unless she was required to do something for them. And, there was no proof put forward in the series that Nina recruited Jamey. But, even if she did, it would be the perfect motive to kill her.