The Profiler: Agent Patterson and his team. And of course Mulder.
Red Herring: The killer bit Agent Nemhauser and it's frequently mentioned and shown. Mulder's a bit of one, too, although they obviously realized that no one was going to believe he had become a serial killer, necessitating Nemhauser's presence.
Room Full of Crazy: There are sketches of gargoyles all over the walls in Mulder's apartment.
Serial Killer: A very disturbing one who kills young men via blood loss due to facial mutilation, in an attempt to re-create the gargoyle-like evil face he claims to see.
Surpassed the Teacher: Agent Patterson has a strange but understandable attitude towards Mulder. He feels that he threw away his amazing talent and instead of profiling criminals he chose to chase aliens and the paranormal. Mulder thinks that Patterson never thought highly of him. However, Patterson is probably a bit envious of Mulder's abilities and according to his team, he starts telling "Mulder stories" about him being "some kind of crack genius" when he's drunk.
Tuckerization: Agent Nemhauser is named after the executive producer Lori Jo Nemhauser.