Nathan is Alex's neighbour in their apartment building. Alex and Nathan first meet in the episode Free, after Alex is promoted to field agent in All the Way and is given a new home outside of Division to live in until activated again, not knowing she has been implanted with a kill chip at the base of her cortex.
Nathan attempts to help her with her bags after she has been shopping, and invites her to a party he is throwing that night. However, Nathan is wary when Alex very professionally uses self defense to cast off unwanted attention from one of its partygoers (the owner of the building's son). She leaves in a panic, and Nathan confronts her about it later.
Nikita spots signs of Alex and Nathan's relationship beginning to take a romantic turn, and she warns Alex that Division will know if she proceeds. Regardless, Alex and Nathan begin their relationship in The Next Seduction.
In Echoes, Alex runs into a part of her dream that she has imagined in her own apartment. She is searching for the younger version of herself she has been trying to protect throughout her dream, yet finds that, in this scenario, she and Nathan are married with a young daughter. Towards the end of her dream, Alex must fight a version of herself that she is scared to become, the Udinov heiress, from shooting her two potential family memebers.
Nathan is forced to kill Jaden in Betrayals to stop her from stabbing Alex after she realises Alex has told Nathan about Division.