The ability to be aware that one's Universe is fictional, and potentially use this to act in otherwise impossible ways within their fictional universe.
Fourth Wall Breaking
Users have the capacity to be aware that their Universe is false. Through this, they may be able to carry out acts that, within the Universe, would otherwise be impossible. Depending on the extent of the user's power, one could potentially gain the powers of Reality Warping and/or Omniscience within the context of their own false Universe.
Deadpool (Marvel) shows awareness that he is in an illustrated story.
Uatu the Watcher (Marvel)
Pinkie Pie (My Little Pony: Frendship is Magic) can view and shatter the fourth wall.
Ajimu (Medaka Box) is aware that she is in a manga and will be animated.
Neo (The Matrix) is aware that The Matrix is a false existence, and as such can manipulate its reality, stopping bullets in their paths.
The title character of the film Rango is aware of the fact that he's a fictional character in the film.
Many Kid Icarus: Uprising characters like Pit and Viridi, often break 4th wall by making video games references or mentioning that they're in a video game themselves
Sonic talking to the audience in the show's segment "Sonic Sez"
Lyssa Drak (DC)
Kirihime Nastuno - "The protagonist has enter the story." (Dog & Scissors)
Kuzco (The Emperor's New Groove)
Scott Pilgrim (Scott Pilgrim comics) frequently shows an awareness that he's in a fictional universe, telling many other characters to "read the book" when they ask questions regarding the events of previous chapters or volumes.
The Squid Sisters (Splatoon), Callie (left) and Marie (right), are aware that they are in a video game and occasionally reference that fact.
The Twelfth Doctor tells the viewers to Google the bootstrap paradox (Doctor Who)
Neptune (Hyperdimension Neptunia) Breaks the fourth wall
Uncle Grandpa (Uncel Grandpa) is shown to be aware of the fact that he is in a cartoon, and would sometimes acknowledge the fictional world around him and the viewer.
Sardonyx (Steven Universe) is implied to have a limited awareness of the fictional nature of her show, making references to it as she gets to know Smoky Quartz, such as reffering to one of the voice actors and to Cartoon Network itself.