Creepy Mortician: Or in this case, FBI arson specialist. The first thing we see of him as he is shown a slideshow consisting of fires that spontaneously erupted on - and killed - a member of the British aristocracy is him hugging the projector screen while gushing about how beautiful the fire is. He's even a little jealous that it's Mulder on the case and not himself.
External Combustion: Mulder and Scully get into their car and find a strange cassette tape on the dashboard. They pop it in, and a voice informs them that by doing so they have armed a bomb hooked up to the car, and opening the door will trigger the explosion. Someone then opens the door from the outside, and Scully jumps—turns out the voice on the tape was just Mulder's New Old Flame, trying to mess with their heads.
Finger Snap Lighter: Cecil L'ively lights his finger to mess with a young woman at a bar. He also lights his cigarettes completely hands-free on several occasions.
Healing Factor: Cecil's ability to heal is pretty extreme, as is revealed at the end of the episode. He not only survives getting fifth to sixth degree burns over most of his body, where a fourth degree burn is often lethal, he is shown to be recovering within weeks.
Kick the Dog: Cecil has two. Near the beginning, he literally kicks and berates a dog that is about to expose the corpse of the caretaker he is impersonating. Later, after taking time out to show the Marsden children a series of magic tricks with a cigarette (which on its own might have been a Pet the Dog moment), he rather aggressively tries to convince them to smoke.
UST: Scully is supposed to hate Phoebe, and she's not too fond of her, but more than anything she's annoyed with Mulder's non-professionalism. Dancing and kissing while he should be looking out for a suspect. Seriously, Mulder, you're an FBI agent.
Why Did It Have to Be Snakes?: Mulder is deathly afraid of fire, and guess what he has to face. However, it is not that much of a coincidence, as Phoebe Green brought him on the case on purpose.