Jason Nichols (played by Joseph Fuqua and Michael Fairman) was a graduate student at the Massachusetts Institute of Technology who was working in cryobiology. Along with Lucas Menard and Lisa Ianelli, he was completing a thesis on cryobiology applications in which living organic tissue could be preserved indefinitely and thawed and revived later. However, Inelli fabricated some of the findings to ensure that Nichols would be rewarded an NSA grant. Menard, also seeking the grant, learned of the fabricated evidence and threatened to report it. He and Nichols were arguing while leaving one evening and an old man warned them to stay away from a certain street and that Menard would be hit by a bus. He was apprehended and taken away by campus police. However, Menard was then struck and killed by a bus as predicted.
Nichols was taken into custody because it had appeared that he pushed Menard in front of the bus. Mulder and Scully were brought in after the discovery of the dead campus police officer - whose corpse had been frozen solid. They learned about Nichols' experiments with cryobiology from Inelli. That and the competition for the NSA grant painted a bleak picture for Nichols. The situation became worse with the arrival of Dr. Yonechi, who was found frozen as well. However, he burst into flames upon revival and died. Inelli encountered the old man who had seen Nichols earlier, and he said he intended to kill her, but let her go. Mulder and Scully discovered the old man's apartment and found a photograph of Nichols, Inelli, and Yonechi - yet the three of them had never met. Mulder theorized that the old man was a visitor from the future who had come back in time to alter it by changing the past. However outlandish, this proved to be true.
The old man was Jason Nichols from the future who had come back to prevent time travel from being invented. After the discovery of tachyons, Inelli would find a way to travel through time using cryobiology. The compound the old man used was one Nichols had been developing but was still five to ten years from completion. The old Nichols injected Inelli with the freezing compound, but Scully was able to save her. Meanwhile, Nichols tried to protect the computer mainframe on which his files were kept. Of course, the old man was there trying to delete them. When they encountered each other, the young Nichols was furious but his older self exhorted him to save the future. Without treatment for the feverish effects of the cryo-compound, the old Nichols burst into flames as Yonechi had and died while taking his younger self with him.