Can all fanfictions be considered as alternate universe?

[OP1000]

I personally have a head canon that every fanfiction protagonist exists in an identical alternative dimension to the original, and the reason it they are in an alternative instead of the original is because if they existed in the original, they would ruin all alternatives and permanently affect the entire fictional reality.

As for my personal little works that I dabble in, they all take place in alternative universes with slight differences that can have surprising effects - like what if Izuku Midoriya wasn't a little bitch, a useless rag emotionally, or a doormat - what if they had different attacks, like instead of the Detroit Smash!, they had the Mississippi Dash!, Alaskan Bullet!, or the Arizona Impact!, which could be a long-distance coverage move, pressure-point attack, and axe-kick move respectively?

Sorry for the late response. But man do I like the names Izuku's attacks that you came up with in your comment.

 

[Representing_Tromba]

I would say yes. Even Narnia is a Bible au fanfic

 

[Fox-Trot-9]

AU denotes a retelling of the original source material with an alternation of a major part of the story, like a new genre setting, or a different direction of the original plot line, or a mashup with another fandom, or an OOC version of original characters. Examples include slash / femslash fan fiction, fairy tale retellings, Hardy Boys / Nancy Drew crossover books, The New 52 comics, the 2016 Ghostbusters reboot, Batman movie remakes, Superman movie remakes, Alice movie remakes, etc.

But not all fan fiction is like that. Fan fiction can also have additional episodes, story arcs, and new characters, stuff that can conceivably be left out of the original canon but still remain part of its extended universe. Examples include Star Wars' Expanded Universe, the Marvel Cinematic Universe, the DC Extended Universe, etc.

 

[beast_regards]

Theoretically, though, some consider themselves sequels, prequels, reboots or re-imagining. If you get actual permission for it, it's most likely called adaptations, not re-imaginings.