Rachel T. McKenzie is one of the sternest operative in the KND aside from Numbuh 1. She is serious about the KND's mission, but she is also willing to look past the mission to the well-being of her charges. She is also stubborn, serious, but she is kind, supportive, smart, organized, and friendly, though, she is quite impatient and disapproves for Numbuh 1's reckless attitude as shown in Operation: Z.E.R.O. and in Operation: I.T., it is shown she dislikes pressure. Rachel is always very practical and logical, as she does not believe in myths such as Numbuh 0 until it is proven to her. She was originally known as the best espionage agent in the KND until Numbuh 274 betrayed the organization, where she took his place as the Supreme Leader.
Numbuh 362 hinted that she has feelings for Numbuh 1 throughout the episode as she is seen constantly dragging him away from his girlfriend, Lizzie Devine, stating the KND Splinter Cell were invading the KND and would often call him by the nickname "soldier". Immediately after Lizzie broke up with Numbuh 1, recalling the fact that he cared more for his duties in the KND then dating her, Numbuh 362 arrives and tries to cheer Numbuh 1 up by asking him out to get a meatball sandwich, which he turns her down. Rachel left with a sad look on her face and told Nigel, "I understand. You know where I am if you want to talk. See ya around, soldier," before taking off.
Rachel still commanding most of the KND operative after the invasions, she also struggling a plan to take back their world even the cost of her own life.