There's an episode [Normal Again, Season 6] of Buffy the Vampire Slayer where Buffy is struck by a demon's talons and she is poisoned. She wakes to find herself being stabbed with needles by orderlies in an asylum. She starts having these vivid episodes where she is in a patient mental hospital. A doctor calmly informs her that she has been sick for years and that the entire "slayer" role and her gang of friends are all a figment of her imagination, to help her feel like she is special and that she has a role in the world. In these "hallucinations" we see that her previously thought dead mother is actually alive and that her parents never divorced. With the coaxing and therapy of her doctor, she decides that she prefers this "normal" life with her parents and Buffy attempts to destroy the things that tether her to the "fantasy" life of the Slayer: her friends. She almost does, but at the last moment, the antidote is shoved down her throat and she realizes what she is doing. However, because Joss Whedon is a sick bastard, he crafts the episode so that in the end, the audience is left wondering if the possibility that the real Buffy Summers is actually a very sick and scared child is actually the real truth, and that the previous 6 seasons of this television show have been a lie.
"Cause what’s more real? A sick girl in an institution, or some kind of supergirl, chosen to fight demons and save the world? That’s ridiculous."
What if I'm a crazy kid in a mental institution?
[God. This is why I need to stop listening to Avril.]