Nathan and Bryan's relationship started at some point on the Ark. They were separated when Nathan was locked up in the Sky Box for stealing. Later Nathan was sent to Earth with the other Delinquents. When the rest of the Ark came down to Earth, Bryan was on Farm Station, landing in Ice Nation territory. After Farm Station rejoined the rest of the Sky People, Nathan and Bryan were reunited. They share living quarters at Arkadia.
Both Nathan and Bryan serve on the Arkadia Guard. The unrest within Arkadia puts them on opposite sides of the internal rebellion, with Bryan following Pike and Nathan helping Kane, creating a strain on their relationship.
In Season Four, their relationship is unstable. While trying to retrieve the hydro-generator from Farm Station, Nathan and Bryan come into conflict on whether saving a few people now is worth potential loss of many people later, leaving their relationship uncertain. Bryan is left outside of the Second Dawn Bunker, and perishes during Praimfaya. Their relationship is officially confirmed over when, as seen during flashbacks in "Red Queen", Miller is now dating Jackson.
In Terms and Conditions, Bryan enters their quarters just as Nathan is getting reading to leave for work. They speak about not seeing each other often due to having opposite shifts, with Bryan working days and Nathan working nights. The conversation switches to Pike's politics, which is a sensitive topic since Bryan stands behind their Chancellor while Nathan supports Kane. Bryan helps Nathan put his jacket on and they kiss goodbye before Nathan leaves for work. To help find traitors for Pike, Bryan places a bug inside Nathan's jacket but feels guilty and unsure about his actions. At the end of the episode, they sit together, outdoors around a fire.
In Stealing Fire, Nathan finds out about Bryan's bug and confronts him. Bryan tells Nathan he loves him but Nathan responds that he "can't have both of them." Later, Bryan helps Nathan with his plan to help Kane, Sinclair and Lincoln escape.
In Demons, Nathan tells Harper a ghost story much to the dislike of Bryan. In the midst of this, Nathan spooks Bryan as a joke.
In Heavy Lies the Crown, the group wants to obtain the hydro-generator from Farm Station so water could be generated within Arkadia. Since Bryan is the only one who knows where Farm Station is, he leads a group of five there. There they find Azgeda slavers have taken over the station. The group has to decide between using the hydro-generator as a bomb to free the slaves or abandoning the slaves, including Riley, and taking the hydro-generator back to Arkadia. Nathan and Monty argue that survival of 500 Sky People is more important than freeing 25 slaves. However, Byran refuses to leave his friend, Riley, behind. Harper and Bellamy side with Bryan, and the group blows up the hydro-generator, successfully freeing the slaves. Back at Arkadia, Nathan and Bryan argue. When Nathan refuses to agree with Bryan that saving the slaves was "worth it", Bryan storms off.
In The Four Horsemen, Bryan is mentioned by Murphy when he says "Bryan would probably kick my ass" if he flirts with Nathan. Nathan is left uncomfortable and shares a look with his dad.