Supernatural (TV series)/Recap/S01/E22 Devil's Trap

Season 1, Episode 22:

Devil's Trap
To get some help, Sam and Dean visit Bobby Singer, an old family friend who runs a garage and a low-rent "mission control" for hunters in the field. Meg tracks them down, but in coming after the brothers she gets caught in Bobby's "devil's trap", a pentacle within a circle with a series of symbols, all of which work together to trap certain supernatural creatures. Once Meg is captured, they realise that Meg is actually a demon from Hell, using an innocent human as a vessel, and that Yellow Eyes is also a demon and a very senior, very powerful one. The brothers and Bobby exorcise the demon from Meg, and she's able to give John's location before she dies.

The brothers travel to Missouri, rescue their father and retreat to a cabin to regroup, but it turns out that the Yellow-Eyed Demon is now using John as a vessel. As he tortures Dean, John temporarily manages to regain control and begs Sam to use the Colt, killing him and the Yellow-Eyed Demon at the same time, but Sam can't bring himself to do it and shoots John in the leg instead. The demon flees, and the brothers are taking John to the hospital when the Impala is run off the road by a truckie possessed by the Yellow-Eyed Demon.

Tropes

 * All in the Eyes: Demon!John gets this treatment throughout the torture scene.
 * Soundtrack Dissonance: "Bad Moon Rising," played cheerily over the final scene.
 * This Is for Emphasis, Bitch