- What is this for a zombie apocalypse?
- — To Alex at her apartment
Nathan Colville is Alex's neighbor in their apartment building. Alex and Nathan first meet in the episode Free, at first Nathan was just her neighbor then they started to have a connection. Alex said that she was not in a relationship with Nathan, but secretly was
In "Free" Nathan attempts to help Alex 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 defence to cast off unwanted attention on this party from one of its partygoers. She leaves in a panic, and Nathan confronts her about it.
In "The Next Seduction" he was invited to a dinner with Alex and her boss Michael. 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 "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 members. In the same episode, Nathan comes across Nikita scavenging through Alex's apartment.
In "Covenant" Nathan tried to persuade Alex to tell him her secret. They ended up having sex.
In "Girl's Best Friend" Alex dreamed of Nathan as an assassin. In her dream he tried to kill her. Back in the reality she revealed to him that her full name is Alexandra.
In "Glass Houses", Alex tries convincing Nathan to hide at Nikita's safe-house, but he assumed that Alex was indebted to the mob, before Alex admitted that the people she wanted to protect him from are government assassins. Nathan does not believe her and leaves. He later returns some articles of clothing to Alex, just as Jaden is visiting. He sarcastically comments that she must be another government assassin before walking out the door. Unfortunately, this sets off alarm bells for Jaden, who tries to call Division. Nathan comes back into the apartment after hearing Alex and Jaden scuffling and is forced to kill Jaden to stop her from killing Alex. Alex then tells Nathan to run.
He is never seen nor heard from again after "Glass Houses".