Can I answer an old block question?
Bad Blood (Season 5, Episode 12 (thank you Wikipedia))
Mulder and Scully find a mobile home park full of vampires. The POV for the episode keeps alternating between Mulder and Scully, and when it is Scully's POV, Mulder is enigmatic and the town sheriff (played by Luke Wilson) is hot. When it is Mulder's, Scully is whiny and the sheriff is buck-toothed and hideous!
Comic gold!!! Thanks to Wikipedia, I now know that it is Gillian Anderson's favorite episode, also. So be like Gillian and me, and check it out!