Alternate Universe

An alternate universe fanfiction is a fanfiction written with the characters of a series, but the canon plot is dropped in favour of a new plot devised by the author. Common examples of alternate universe plots are-


 * Placing the cast of the series as students in a North American high school. Complicated love triangles tend to ensue.


 * Replacing the setting and/or cast of one series with another (a crossover).


 * Bringing canon characters into World One to act as muses.


 * "What If" stories that make some change to canon and explore the logical result:
 * Changing the cast by killing off a character, bringing one back to life or changing an event so they never died, and then writing the story in a different direction.
 * Changing events and following the original canon characters through a new history. For example, the fic might ask, "What if Picard had never been assimilated?" and then follow the crew of the Enterprise to show how Federation history plays out differently. The change is often small, but the effects tend to snowball.
 * Changing events to put different characters in the spotlight--usually OCs or minor characters, but can be major characters in different roles from the ones they usually occupy. For example, a fic that asked, "What if Bilbo had not found the One Ring?", might have the ring found by orcs or by the Dwarves, changing the focus of LoTR to some other group of characters.


 * Fics that take place in the past or future may sometimes be considered AU.

Signs You're Doing It Right

 * One basic change is made; the rest of the canon stays intact and reacts the way it usually would.
 * The characters react plausibly to their new situations.
 * If a character's personality is changed, a logical reason exists.

Signs You're Doing It Wrong

 * The existence of one or more Mary Sues.
 * Multiple, random changes that have no common theme.
 * Changes that seem to be contrived for the express purpose of realizing a favorite pairing.
 * Only one result of a change is explored--all the others are ignored, even when there should be widespread effects
 * Characters share only their names with their canon counterparts

AUs and the PPC
AU stories are not immune to the attentions of the PPC just because they are marked AU. If a canon character is OOC in ways not explained by the changes in the fic; if there is horrible writing present; if there are one or more Sues, bad slash, illogical plot, or any other signs of badfic, the PPC can and will send agents into AU fics. In fact, the Department of Improbable AUs handles AU fics exclusively, and the Department of Implausible Crossovers handles crossovers.

According to one version of Multiverse Theory, AU continua are part of the Multiverse. Just like there are multiple versions of World One, there are multiple versions of each continuum because a story is never just made of the events in the story--it is also made up of the events that could have happened, but didn't. These "could have" worlds are AU versions of that continuum, some more likely than others, and badfic in these worlds can endanger the canon just like badfic that directly affects the prime version of that continuum.