You Can't Handle the Truth
Supernatural Season 6 Episode 6 (10/29/10)
Sam and Dean take on a case involving people who kill themselves after being bombarded with nasty truths.
Dean is frustrated that he doesn’t know what Sam is and calls Bobby for help, but to no avail.
Dean gains the power of truth and everyone around him starts admitting things.
Dean tries to use his power on Sam and thinks he receives an honest answer.
The boys learn that The Goddess of Truth, posing as a TV reporter, is causing the mayhem and they follow her to her apartment.
The Goddess of Truth captures the brothers and attempts to force them to tell the truth.
She reveals that Sam is not human and that he is unaffected by the truth power.
Sam and Dean kill the Goddess.
Dean confronts Sam a second time and Sam attempts to explain that he doesn’t understand his change. He feels nothing from any action he takes.
Dean punches Sam multiple times leaving him unconscious.