Hello from Italy! I'm trying to create an AU. Can you give me some advices? I don't wanna steal other ideas or create something cringe, but is soo hard with all those universes and outcodes already existing!
You have to leave the whole "I don't want to (accidentally!) create similarities" mindset behind you when you want to create an AU/character in a fandom that has hundreds of them. Similarities are bound to happen and while that sucks (especially when it isn't your intention), you have to be realistic and kind to yourself too: nobody can know about every single AU or OC this fandom has to offer. I still learn about new ones every week, no matter that some AUs/characters may have been around for a few years already. Worrying about these things sucks all the fun out of creating and worldbuilding.
I found out a while after creating Rewind!Sans that there were two Sanses called Rewind back in 2016, three years before I created my own Rewind. And to my relief, all they had in common was the name; their stories, personalities, appearances, and abilities were all very different. AKA, this stuff happens and it is, unfortunately, out of your control.
Although it's difficult to be unique in such a vast AU-powered part of the fandom, it is not impossible! I've come across plenty of AUs that share the same base cast (Frisk, Sans, Papyrus, Undyne, etc), but are still new/different/unique in various ways.
So my advice is very simple; do what you like, create what tickles your fancy. If you have a story to tell, tell it. Don't let these worries and paranoia hold you back but instead allow them to feed your inspiration and help you strive to do differently. All you can do is try and have fun while trying.
If you are aware of a similar idea being out there, keep it in mind and try to make enough differences so your own ideas stand apart.
(A tiny piece of advice I can give is to Google any names you may think of for your AU/characters and see if anyone else thought of them too. If so, it's up to you if you'll stick with them or change them.)
On that note. If you are going to create an AU/character based on someone else's, and they are also okay with it (best check beforehand!), credit them as the inspiration. It's the least you can do. There are plenty of AUs and out!codes out there that were inspired or based on another (like Fellswap, Swapfell, Mafiafell, etc) and there is no shame in piggyback riding these AUs because you are allowed to. Several of them belong to the AU community (like Underswap and Swapfell Red) so you're free to play around with them.
I have around fifteen AUs (some more developed than others) and only four don't use a different AU as a foundation (these are UndeRewind, UnderRealm, Golden Crime, and a so far unnamed AU). The rest was inspired by either Underfell, Swapfell, Underlust, Dreamtale or whatever else. Same goes for several of my out!codes. Whatever feeds your inspiration and whatever tickles your interest.
