This is something I have thought a lot about but just haven’t had the discipline to actually sit down and write.
It’s a Harry Potter and Stranger Things crossover. The ship is Harry x Will. Harry left Hogwarts after the triwizard tournament (whether Voldie is still a problem is up to you) and moves to california where he meets Will. In my version he’s living in the Muggle world under the name Hadrian Peverell and self-studying for his O.W.Ls because of various reasons, and he’s emancipated so he lives by himself. He tutors El in math and English and gets to know Will and they fall for each other. (I hate Byler and Mike/El cause Mike is a total asshat and his relationship with El is not healthy in the slightest) Will learns about Harry’s magic and Harry learns about El’s powers and hypothesizes that her abilities are made possible because unlike most muggles she built her own connection to her magical core* (*see detailed explanation at the bottom) but anyways, Will has angst surrounding being gay in the 80s, Harry has angst because he’s Harry Fucking Potter. This is all before the main plot which is basically a retelling of Season 4 but if Harry was in their lives.
In my version he isn’t around when the early events of volume 4 take place because Will wanted to hang out with Mike and didn't feel it was cool for him to bring a stranger along, he eventually shows up at Will’’s place to find it shot up, he goes looking for him, finds him after they leave Suzie’s and then Will begs him to go help his friends in Hawkins while he goes looking for his sister, Harry does. So you end up with two storylines, Will’s slightly altered version of canon (where the tension between hi and mike gets intense and Mike is demanding to know who Harry is and why Will just outright tells him everything etc), and Harry helping the Hawkins crew battle Vecna. Eddie survives and Max doesn’t end up in a coma in my version, also Harry manages to clear the entire crew of suspicion at one point or another, etc.
I also had this view of a few chapters of epilogue where Will’s friends and Family find out about his and Harry’s real relationship, Will and Robin become Gay Buddies, Steve being the “straight best friend” and also in my version Mike is a total dick, and he and El break up after she realizes what a douche he is to everyone besides her and sides with her brother after soe kind of altercation. When the Byers family moves back to Hawkins, Harry moves too because they are the only family he has. The world doesn’t split open, and Vecna is dead for good etc. El is studied by the wizarding world to determine if her abilities will cause long term damage and to help her develop her core and learn actual spells.
*So basically in this universe, everyone has a magical core, Muggles included. Wizards however are born with a connection to their core and thus are able to harness it and use it. In this fic Brenner essentially forced this connection into existence which is why they have nosebleeds, the strain of focusing the intense power of their core through a forced artificial connection causes stress on the body.
Obviously you can change it to suit your own ideas and preferences, but if you do write it make sure to mark this fic as the inspiration or tag me in it or send me a DM letting me know you wrote it.
I'm also happy to help beta the fic or provide help or smaller ideas if you want, I just don't have the discipline to sit down and write this fic out. Send me a DM if you want me to do one of those things!