“So I’ve never before responded directly to the fandom’s comments about an episode, and I don’t plan to make a habit of it, but I couldn’t resist dropping in a thought about the episode “Yellow Fever.” Which is this: Dean is not a dick. None of the writers, or anyone on the creative team of Supernatural, think Dean’s ever been a dick, past, present, or future. He’s a hero. Dean did NOT contract the ghost sickness because he’s a dick. Victims contract the illness because they use “fear as a weapon.” Dean asks Lilith at the episode’s end, “why did I get infected?” And she cryptically responds, “you know why. Listen to your heart.” We, as the writers, probably should have emphasized this mystery more, I take responsibility for that omission. But the point is: the reason he was infected is because of a SECRET he’s keeping. A dark secret that will be revealed in Episode 10. And not at all because of any dickishness, implied or otherwise. Thanks, gang.”
– Eric Kripke, Creator Supernatural (October 24, 2008)
Heaven and Hell 4.10 is when Dean revealed he’d tortured souls in hell