of Rodney", Rodney's genes are mutated by a device designed to aid with Ascension on the Ancients who were physiologically incapable of doing so. During this time, Rodney invents several equipment upgrades, writes several theories and books, including a biography of Dr. Weir, and optimizes the city's power grid, believing himself a dead man. After accepting that Ascension is his only hope of surviving, Rodney attempts to make amends to his colleagues and gives final gifts to several friends, including healing the massive scarring on Ronon's back. He is later returned to normal at the last minute. McKay takes Dr. Beckett's death in "Sunday" quite badly. He assumes the duty of telling Beckett's mother that her son had died (the two are revealed to be, in fact, close friends) and subsequently serves as one of Beckett's pallbearers. A mourning McKay was comforted at the end of the episode by what appeared to be Beckett's spirit. "Reunion" shows McKay deflated when the newly promoted Colonel Samantha Carter is announced as the new leader of Atlantis after Dr. Weir's condition worsened. McKay tells Carter of his relationship with Katie Brown and that he hopes that the old attraction between them will not get in the way of them working together. In the episode "Quarantine", McKay decides to propose marriage to Katie Brown, but a citywide lockdown traps him and Katie in the botany lab for several hours. McKay ultimately decides not to move forward with his marriage proposal, although Katie is left in the belief that he intended to propose. Katie and Rodney are no longer speaking in "Trio" because she interpreted his recent decision as a break-up and lack of interest, and she adds her name to a list to be transferred back to Earth. At the end of the episode, Dr. Keller asks Rodney out. In an alternate future in the season finale episode, "The Last Man", McKay loses Sheppard, Teyla, Ronon, and Carter, quits the Atlantis expedition team and becomes romantically involved with Dr. Keller. In the episode "The Shrine", Rodney suffers from a disease with symptoms similar to Alzheimer's disease and reveals in a video to Dr. Keller that he has loved her "for some time now". Later, in "Brain Storm", Dr. Keller finally confesses to Rodney their feelings were mutual. McKay is last seen in the episode "Seizure", trying to dial Destiny, but is eventually unable to