Orison

Donnie Pfaster is broken out of prison by a vigilante prison chaplain, Reverend Orison (Scott Wilson), who intends to give Pfaster his own form of justice. However, Orison has bitten off more than he can chew, and Pfaster deals with him and then goes after Scully.

Tropes:

• Big Damn Heroes: Mulder arrives and captures Pfaster after this one ties up Scully and is getting ready to have his way with her, although it's undermined by the fact Scully was in the process of pulling a Damsel out of Distress at that very moment.
• Berserk Button: Pfaster gets rather... upset... when he discovers the call girl he ordered wasn't an actual redhead. It leads to the Eye Scream described below.
• Bound and Gagged: Scully, briefly, after Pfaster manages to tie her up.
• Damsel out of Distress: Scully, after being Bound and Gagged by Pfaster. In a rather tense scene, she manages to slowly crawl away, untie herself, and grab her gun, while he's distracted preparing their bath.
• Deadly Bath: Well, it would be deadly if Pfaster had his way.
• Eye Scream:
  • A call girl throws hot wax from a candle in Pfaster's face before she escapes.
  • At the start of their fight in Scully's apartment, Scully's first move is to stick her thumbs in Pfaster's eyes as a way of making him let go of her.
• Fight Scene: A brutal one between Scully and Pfaster, which results in mutually drawn blood and a lot of broken furniture. Pfaster might be a full foot taller, but Scully is, after all, a fully trained FBI agent.
• Gunman with Three Names: Donald Addie Pfaster.
• Heroic BSoD: Scully, who kills Pfaster in cold blood immediately after he is captured in her apartment. It's also variation on What You Are in the Dark, as she shoots out a lamp beforehand (though she's not actually alone when she goes through with it), and the moral dilemma affects her afterwards.
• Maybe Magic, Maybe Mundane: This episode is rather infamous for downplaying this aspect of "Irresistible", the episode it is the sequel to. In his original appearance, Pfaster was firmly stated to be very much a human antagonist and his brief transformations to something demonic seemed to be Scully's (and others') imagination at work. Here, it leans more heavily on the idea that Pfaster is supernatural in nature, somewhat undermining the Humans Are the Real Monsters element of "Irresistible".
• Religious Horror: As with "Irresistible", a good portion of the episode centers around Scully's faith, the difficult-to-dismiss omens she sees, and her logical forensic investigation skills all agreeing that whatever Pfaster may be, it's evil.
• Retcon: In "Irresistable" Donnie Pfaster was described as a "death fetischist" desecrating already dead bodies that had recently moved on to killing to satisfy his urges, and he only successfully killed one victim. In this episode he is said to be a serial killer convicted of five murders.
• The One That Got Away: A very dark example. Pfaster specifically calls Scully this.
• Sequel Episode: To "Irresistible".
• Sherlock Can Read: Lampshaded and subverted. When Scully questions Reverend Orison he says he can sense she has faith and that she is unsure what God wants of her. Scully, unimpressed, points to her very visible cross necklace and says it was hardly a long shot to assume that. Then the Reverend calls her by the Affectionate Nickname her childhood Sunday school teacher called her, which does rattle her as he had no way of knowing or guessing it.
• Slow Motion: Scully's gun firing dramatically in slow motion near the end, and the closeup on her face.