Book Ends: Mulder and Scully investigate in Bellefleur, Oregon, which was the place of their very first assignment. They see a faded X sign on the road, which Mulder painted there to mark an anomalous electrical disturbance back then. They also meet some of the same people, some of which are multiple alien abductees. In both episodes, Mulder and Scully have a personal conversation in a hotel room — in the pilot Mulder tells her "nothing else matters to [him]" except his quest, while in "Requiem", he insists that the quest isn't worth sacrificing her health and happiness.
Myth Arc: Alien abductees are back, Skinner, Kryczek, Marita... they all make an appearance.
Series Fauxnale: Mulder and Scully return to the site of their first case together, pretty much every major character gets an appearance, and the episode ends in true X-Files fashion in which Mulder is abducted and Scully finds out she's pregnant without conclusion or explanation for either. A lot of fans treat it this way, since many regard season's 8 and 9 as subpar to the rest of the series.