Following an unexplained spate of babies being born with tails in a small town, Mulder and Scully search for a man who possesses the ability to change form.
Tropes present in this episode:
Almost Kiss: Between Scully and "Mulder". Mulder busts through the door just in time to put a kibosh on it.
Bait and Switch: Apparently, after attacking Mulder from the ceiling, he up and escaped, meaning the case is closed and Mulder and Scully can leave... until the actual Mulder is revealed to be locked in Eddie's janitor closet.
Bed Trick: Eddie's shape-shifting abilities allow him to pull this on women.
The Cameo: All we see of Skinner is when "Mulder" and Scully meet with him after Eddie (supposedly) escapes.
Scully: Van Blundht somehow physically transformed into his captor, and then walked out the door, leaving no one the wiser?
Mulder: Scully, should we be picking out china patterns, or what?
Epic Fail: "Mulder" somehow managed to misspell "Federal Bureau of Investigation". Twice.
While Mulder is looking over Eddie Sr.'s corpse, Scully mentions how good it is that it's intact... immediately before Mulder snaps the tail off. He then distracts Scully long enough to try and fix it, "try" being the key word.
Foreshadowing: When Mulder is questioning Amanda the second time, his responses to some of her answers about Eddie foreshadow the fact that it's not actually Mulder.
Idiot Ball: Scully notices that "Mulder" is behaving a bit weird, but fails to connect this with the disappearance of their recent shape-shifting suspect (who was using his ability to essentially rape women by impersonating men they were attracted to). Fridge Brilliance suggests that she likes this new Mulder too much to admit her suspicions.
Less forgivable, however, are the unnamed husband and wife who buy "Mulder"'s story of chasing Eddie into their bathroom, having to get people to come and dust fingerprints, and also needing one of the husband's suits. Especially jarring since the wife saw "Mulder" enter the bathroom... as "her husband".
Know When to Fold 'Em: After Mulder bursts in during Scully and "Mulder"'s kiss, Eddie simply reverts to his normal form and gives up.
Logical Weakness: After Eddie is incarcerated, he's given muscle relaxants to keep him from shapeshifting.
Moment Killer: "Mulder" and Scully's kiss is ruined... by Mulder bursting into Scully's apartment.
My Nayme Is: Played with. The unusual spelling of Eddie's name is real, but his insistence on the proper spelling and irritation when it's misspelled certainly fit. He probably makes such a big deal out of it because the spelling makes him feel special.
Oh Crap!: When the husband Eddie is impersonating arrives while he's in the bathroom.
Similarly, when he leaves Angie's room as Mulder... and almost bumps into Mulder, who's looking for said room.
Power Incontinence: It's implied that Eddie has trouble holding another form for a long period of time.
Red Herring: The teaser suggests that the case with be connected to alien abductions and medical rapes and impregnations as Amanda said the father of her child is not from this planet. However, it deals with babies having tails.
Running Gag: Eddie van Blundht's name. "The 'h' is silent."