Sean was always known to play with the affections of teenage girls, as he made a move on Chloe Sullivan.
While playing football, he fell into an icy lake, infested with kryptonite, and gets trapped within it. He manages to free himself, but his skin was turned blue with cold. Warming his hands at a small fire, he absorbs the heat out of the fire and warms himself. Sean realizes that by stealing the body heat of others, he stays warm for at least a day, trading the survival of others for his own. Sean pays a visit to his girlfriend, Jenna Barnum, and steals her body heat, turning her body to ice which shatters. He then set his sights on Chloe, but she was saved by Clark Kent.
By absorbing Clark's heat, he is strengthened, but Clark manages to survive it. As he tries to drain the heat from other people, Clark manages to hurl him into a nearby pond. Sean, unable to control his power, sucks the heat from the water around him, encasing himself in ice.
Chloe and Pete Ross discovered a secret underground laboratory built by Dr. Donovan Jamison, Dr. Steven Hamilton, and Dr. Arthur Walsh. The doctors were mining and using kryptonite to try and find a cure for meteor freaks. They had the bodies of several meteor freaks, including the frozen body of Sean Kelvin. Sean was barely alive, encased in a block of ice.
Chloe and Pete caused an explosion. As they left the lab, they saw Sean's block of ice melting as they climbed out to safety. His current whereabouts are unknown, but it is unknown if he is alive, however, due to the heat of the fire caused by the explosion, it can be assumed he survived. It is unknown whether the explosion killed him though.
- Degrees Kelvin is sometimes used to describe very cold temperatures. Sean's last name is a reference to the power he gained.