CuckooNest

Fics where the character wakes up in 'The Real World' and is told that their entire life was a coma dream or a delusion. More info at TV Tropes.

Death Note

** Wonderland by RobinRocks

T, Complete, L/Light,<5,000

- Light Yagami awoke to white walls. Screaming. Written for LxLight Club's Alternate Ending contest. Onesided LightxL.

Metal Gear Solid

Through a Glass, Darkly by Athena Crickey

K+, Complete, Snake/Otacon

- One man's reality is another man's dream. But Snake's never had time for pithy philosophising.