Seth Dormer was a cadet at the S.H.I.E.L.D. Academy (Science Division), and was Donnie Gill's classmate.
Seth was a popular student at the S.H.I.E.L.D. Academy when he contacted Ian Quinn to try to sell Quinn Worldwide a weapon, wanting to make himself rich. Quinn agreed to make a deal, as long as the weapon worked. At the Academy, Seth befriended Donnie and pressured him to make the weapon.
The weapon in question was an Atmospheric Moisture Freezing Device, made from the crystalline nucleation process hypothesized by Jemma Simmons and the delivery device designed by Leo Fitz, both scientists being legends among the Academy. However, the device was faulty, and would go off uncontrollably and randomly. One such incident nearly trapped Seth and other students underneath a layer of ice in the Academy pool, drawing attention to Donnie's freezing device.
After running off with Donnie to demonstrate the weapon to Quinn, Seth set off a superstorm of lighting, wind and hail in an empty lot. Trying to deactivate the out-of-control device, it exploded and sent the two boys flying. Although Coulson and his team picked up the boys, Seth died from his injuries.
Seth displayed most of the classic traits of the 'golden boy', with good social skills, an unmistakable, easy charm and little concern for the future or consequences. He genuinely liked Donny, but still got irritated whenever his friend tried to intrude reality into the fairy tale he span around himself.