YMMV / The Devil's Only Friend

• Creepy Awesome: Rack. His true form is one of the creepiest in the series, far easier and more realistic to visualize than Crowley's, but using a spare few of nightmarish differences from Forman's to drive home his monstrousness.
• Ho Yay: John's instant attraction to Elijah comes off like....well, an attraction. Particularly his anger and confusion at connecting with somebody who isn't Marci. He even outright says it's a dishonor to her memory, like somebody who lost a partner and is upset with themselves for falling in love again.
  • It doesn't hurt that Elijah's "I thought you were different" speech sounds like a very different kind of speech.
• One-Scene Wonder / Ensemble Dark Horse: Mary Gardner, the Poisonous Person John kills just before the real villain rears his head. She's beloved for her power, unexpectedly vicious manner, and the impact of her fight scene.
• Shocking Moments: John losing it like he feared the entire first trilogy and stabbing the shit out of Agarin, and his killing a human near the end of the book. This one-two Gut Punch is commonly theorized to be the bomb Dan talked about in the Next of Kin dedication.
• Too Cool to Live: The FBI strike team, particularly Elijah and Diana. A moral demon Foil to John, the goodhearted sociopath, and a badass-yet-empathetic Friendly Sniper. Of course neither of them could stay.