Season 2, Episode 9:
Sam and Dean follow up on one of Sam's visions: Dean killing a young unarmed man. They discover that Rivergrove, Oregon is being torn apart by Croatoan, a demonic virus that turns people into homicidal maniacs. The brothers attempt to defend themselves and the last of the survivors, but just as it appears that Sam has been infected, all the victims suddenly disappear. A blood test reveals that Sam isn't infected and they leave town. In the tag, Duane is revealed to be a demon: he contacts his master using the Goblet of Bloodnote and reports that Sam is immune to the virus. Dean reveals to Sam that he has been burdened by something their father told him just before he died, something concerning Sam.
Body countFor this episode = 4 humans are witnessed to die; the fate of the remaining townspeople is uncertain.For the series so far = At least 165 humans; 11 ghosts; 5 vampires; 1 demon; 1 god; 1 rakshasa; 1 rawhead; 1 shapeshifter; 1 shtriga; 1 wendigo; 1 zombie.
- All Just a Dream: The opening teaser with Dean shooting Duane as he protests that "it isn't in" him is revealed to be a vision of Sam's.
- Artistic License – Medicine:
- There are no lymphocytes in the blood sample Dr. Lee looks at under the microscope, though she reports the percentage is high.
- Anything in the blood at a high-enough concentration to be forming large clumps like the sulfur would likely cause a blocked blood flow and result in heart attacks, stroke, and ischemia to other parts of the body.
- Ax-Crazy: Everyone with the disease.
- Continuity Nod: Duane talks to another being about the virus and the Winchesters through a goblet of blood in the pickup, just as we saw Meg do in "Scarecrow" (S01, E11) and "Shadow" (S01, E16).
- Despair Speech
- Evil All Along: Turns out the reason Duane Tanner knew he didn't have the virus was that he's possessed by a demon.
- Hate Plague: The demonic virus.
- Hulking Out:Dean: For what? For him to Hulk out and infect somebody else?
- I Did What I Had to Do: Dean's rationale for shooting the infected Mrs. Tanner.
- Impostor Exposing Test: Subverted—they should have been checking for demonic possession as well as The Virus.
- Lockdown: The bridge out of town is blocked by townspeople with guns, who say it is part of a "quarantine".
- MacGyvering: Sam and Dean make explosives out of alcohol and other supplies in the medical clinic.
- My Greatest Failure:Dean: I'm already starting to feel like this is the one that got away.
- My Parents Are Dead: Inverted Trope. Everyone in the room knows that Duane is now an orphan because of Dean's actions except for Duane.Duane Tanner: Has anybody seen my mom and dad?Dean: [quietly] Awkward.
- Noisy Guns: Somewhat more slide-racking than really necessary.
- Phones Are Useless: There is no cell service and the land lines are out, as is the police radio in the Impala.
- Plague Zombie: The infected townspeople.
- Shoot the Dog: Dean killing the infected Mrs. Tanner.
- Sam and Dean are familiar with Schoolhouse Rock.Sam: Dean, did you pay any attention in history class?Dean: Yeah! Shots heard 'round the world, how bills become laws...Sam: That's not school, that's Schoolhouse Rock!
- There's a reference to Mister Rogers' Neighborhood.Mark: My neighbor...Mr. Rogers, he—Dean: You've got a neighbor named "Mr. Rogers"?Mark: Not anymore.
- Dean says he feels like Chuck Heston in The Omega Man.
- This town is 40 miles away from Sidewinder. The Overlook Hotel in The Shining is 40 miles away from a town of the same name.
- When thinking about their situation, Dean remarks that "Night of the Living Dead didn't exactly end pretty".
- Dean has a few things he wants to do on the next road trip:
- Sam and Dean are familiar with Schoolhouse Rock.
- Slashed Throat: Mark.
- Stepford Smiler: After meeting Mr. Tanner and Jake, Dean invokes this trope.Dean: That was kind of creepy, right? A little too Stepford?
- Stock Unsolved Mysteries: Sam suggests the inhabitants of the lost colony of Roanoke Island may have been victims of a demonic plague. He also mentions that John Winchester had a theory that "Croatoan" is actually the name of a demon of plague and pestilence, who is also sometimes called "Deva" or "Reesha".
- Stupidest Thing I've Ever Heard:Sam: This is the dumbest thing you've ever done.Dean: I don't know about that...remember that waitress in Tampa?
- Technically Living Zombie: They are transformed by the virus, but do not join The Undead.
- That One Case: Referenced by Dean."You know, I'm already starting to feel like this is the one that got away."
- Themed Aliases: The brothers introduce themselves as US Marshals Billy Gibbons and Frank Beard, after the guitarist and drummer of ZZ Top.
- The Unreveal: Dean twice almost tells Sam what their father whispered to him before John died: once when he thought Sam was infected, but was interrupted when Dr. Lee returned, and then again at the end of the episode creating a cliffhanger.Dean: He told me something about you.Sam: What? Dean, what did he tell you?[END OF EPISODE]
- The Unsolved Mystery: The purpose and creator of the virus remain unknown, as does how Sam's immunity fits into the plan.
- Unexpectedly Abandoned: Rivergrove, Oregon became a Ghost Town in the space of a few hours with no explanation.
- The Virus: Later to be known as the Croatoan virus.
- Would Hurt a Child: One of the effects of the virus, as seen by the blood covering the rear-facing booster seat in the car Dean finds stopped by the road next to a blood-covered knife.
- Zombie Infectee: Mrs. Tanner, Sam, and (we thought at the time) Duane all wait, worried that they will show signs of infection and transform.