Nikki Betancourt joins the team in "High Exposure", though she resents being seen as a newbie, having spent the previous four years in the LAPD. She is originally a little prickly about the FBI's high-tech approach, and not remotely interested in Charlie's math and analogies, but she warms to him, and the team.
Nikki has express political ambitions, with no intention of sitting behind an FBI desk indefinitely, although in "Cause and Effect" it does seem as though she plans to stay with the FBI remainder of the team for the time being at least. She is a dedicated, clever and loyal agent who soon overcomes the chip on her shoulder. David, in particular, seems to frequently rely on her instincts and judgement.