this may not turn out to be the genius play they think it is by May

There’s a quote earlier in the book where Chigurh is about to kill Wells and says to him:

How does a man decide in what order to abandon his life?

Moss is driven by his own code: protect Carla Jean from retribution for his theft of the drug money.
It’s Moss’ slip with the hitchhiker/pool girl that leads directly to his undoing

This is the last time we see him in the book, too.

So I this theory about the book/story. Chigurh is evil incarnate. He’s figured as this almost supernatural force. And he’s driven by a perverse anti-moral code — the coin toss.

They rent two rooms, but Moss turns up at the girl’s room with beer and they have a final interaction. It’s pretty clear from the book that Moss *doesnt* sleep with the girl, but that he’s drawn to her and even being there with her is an abrogation of his moral code.

In the book, there’s no motel swimming pool.
Moss picks up a 16 yo hitchhiker and they go to a diner and then check in to the motel. It’s clear the married Moss knows he is taking an unnecessary risk.

Up until here, Moss’ motivation is to elude Chigurh and keep his wife Carla Jean safe from retribution. By interacting with the girl by the pool, he wavers in his moral framework, and this allows space for Chigurh’s perverse moral order to triumph.

Everything else is implied, but to me it’s clear that this pivotal moment is where Moss abandons his moral authority in the narrative, and Chigurh (aka the devil) catches up with him. It’s the last time we see Moss before he dies offscreen.