Kyle (Traveler 5542) was a high school student and football player at the same school as Trevor Holden. He was one of Trevor's friends and the two remained close after Trevor was overwritten by Traveler 0115.
The high school student was fated to die in a traffic accident when he was driving while intoxicated. The actions of the Travelers in the 21st century seem to have influenced this outcome.
Kyle was first seen at the illegal cage fight in which Trevor was fated to die. He told Trevor that he should stay down because the other guy was good, but Trevor ignored him. The following day, he showed Trevor to his locker and reminded him of the combination, as Trevor claimed to have 'forgotten' as a result of his concussion. (Travelers)
As later revealed, Kyle was continually molested by his football coach, Carson Perry. He quit the team as a result of the lingering trauma. When Trevor asked him why he'd quit, Kyle assumed Trevor was pretending not to remember and angrily reminded him of the abuse they'd both suffered. Kyle also revealed that Perry was molesting other boys.
Trevor tried to convince Kyle to help him expose Perry and make him pay for his crimes. However, Kyle only wanted to move on with his life, and continuing to talk about his abuse was triggering for him. He seemed to be showing symptoms of post-traumatic stress disorder. He turned to alcohol to cope and began exhibiting self-destructive behavior. When Trevor reached out to help him, along with Grace's help, Kyle was sat in his car, drinking and eventually drives recklessly enough that he would've died in a car crash without a consciousness transfer. (Update)
The newly arrived Traveler stumbled out of the car and struggled to remain on his feet, believing his host was somehow damaged. Trevor and Philip revealed to him that he was just drunk. After sobering up Kyle joined Hall and Luca, his new teammates.
The Traveler trio were later assigned to protect Anna Hamilton from assassination by the Faction. Working together with the core team, Kyle and his teammates successfully held off the assault until Trevor was able to destroy the Faction's STA, allowing the Director to overwrite or kill all the assailants. (21C)
At some point Kyle himself was recruited by the Faction. It is unspecified when this occurred, but it was likely after the assassination attempt as Kyle made no attempt of his own to harm the future President. Together with fellow defector Luca he turned on Hall during a firefight. Kyle seemed willing to kill Hall but Luca insisted on doing it himself. The two aided in a mass kidnapping of historians. Kyle posed as a victim to avoid suspicion. The core team (minus Philip) discovered Kyle's defection by using a black box on Hall to recover his memories.
Confined to a small room with Philip Pearson, Kyle continued the ruse by revealing seemingly coerced information to Dawn, their captor. He told them about a police officer who was fated to die later that day; Faction agents saved the man and removed evidence of their presence. Kyle tried to recruit Philip to the cause by pointing out how he'd saved a man's life. He also brought up an incident at the fifth update when a historian died from the side effects. Kyle gave himself away entirely when teams of Travelers assaulted the Faction compound; he and Luca tried to stop Philip from leaving. Kyle was about to kill Philip when Carly Shannon shot him in the back. (Philip)