How would you have rewrite stranger things if you made it?
I would have kept seasons 1 and 2 relatively the same (you'll have to pry The Lost Sister from my cold dead hands). Season 3 is where things would change:
I'm axing the Russian/Soviet plotline. It was such a weird direction for the show to take. Instead, it's Brenner and a small group loyal to him operating under the mall. They opened a gate to perform experiments on Upside Down subjects
Owens is still operating the main lab. There's a small rift in the gate that El closed due to the MF/Henry trying to reopen it, which is how the MF is able to influence things in the main dimension. It's just not as powerful as before. Brenner's people also opened a rift that stemmed from that one like the Soviets did in canon
People leave Mike and El alone. They get to be happy with each other after being separated for so long. Hopper is grumpy about it, but he knows how much both El and Mike suffered without each other so he gets over himself
Will still has his hangups, but not because he has a crush on Mike. He's struggling with feeling like an outsider due to his trauma and coming to terms with his sexuality. I like to think that he accidentally comes out to Dustin while venting his frustration
Max really wants to be friends with El, so she volunteers to be the one to bring El home one night. That's when they start to bond and Max still shows her things like Wonder Woman
The Scoop Troop still exists but Dustin and Steve make the connection to the lab. That stays relatively the same, except it happens much later in the season which gives Dustin time with the Party
Scott joins the group instead of Murray
Instead of wanting to kill El, the Mind Flayer wants to corrupt El like it did Henry. Billy's possession still happens, but the Flayed are a mind controlled army instead of turning into monsters
Nancy and Jonathan are still interning and investigating the rat problem, but they run into Kali who returns to Hawkins hunting Brenner. That's how they learn that Brenner is still operating under the mall and connect the rat problem to th Upside Down
The groups all meet up towards the end like they did in canon. Most things are the same, El loses her powers and Billy dies defending El. The main difference in ending is that Hopper actually dies in the explosion instead of a fakeout. And Kali kills Brenner herself
(I haven't watched season 3 in years so if there's important details missing I'm sorry)
Instead of moving to Lenora with the Byers, El and Kali travel to a secret location to work on getting El's powers back. They're undercover with fake identities provided by Sam, so El is still going to school and having a hard time fitting in while grieving Hopper. But Kali teaches her to embrace being a freak (this leads to El adopting Kali's alt style which isn't important to the plot but it's special to me)
El and Mike talk frequently through Dustin's Cerebro. They use their own secret codes. Kali's insistence on her being herself allows El to open up to Mike a little more than in canon about how she's struggling, which makes Mike sad but he also appreciates her honesty
The Byers are largely out of the picture. Joyce thinks it's best for both Will and Jonathan to be removed from Hawkins permanently in order to be safe and heal. Will actually adjusts pretty well; he misses the Party but after coming out to Dustin he feels more comfortable with himself. Jonathan struggles more, both with distance from Nancy and coming to terms with everything that happened in Hawkins (both the Upside Down stuff and being abused by Lonnie). Weed helps him manage his anxiety
The stuff in Hawkins is mostly the same. Chrissy's death leads to Eddie being suspected while Dustin and the others try to help. The main difference is that Mike is with them. And unknown to everyone including himself, he's starting to experience the same symptoms as Max at a much slower rate
The military blames El for the murders and begins to target her. Sam's able to send a warning message through to El and Kali about both the military and what's happening in Hawkins. They realize how pressed they are for time
To unblock El's powers, Kali tries to figure out what happened between her escaping and El opening the gate. This leads to El remembering the Hawkins Massacre and how she sent Henry to the Upside Down. The trauma of it almost consumes her, but Kali's there to stabilize her. Kali's presence acts as an anchor and it's through facing what happened back then that El's able to reignite her powers
The final fight happens the same way. El piggybacks off Max to fight off Henry. She loses, but is helped by Nancy, Steve, and Robin attacking Vecna's physical body. Max is still kept alive by El restarting her heart. The main difference is that El doesn't try to empathize with Henry yet because her confrontation with Brenner didn't happen
El and Kali return to Hawkins which has been split apart and the season 4 ending still happens
Once given an explanation from Sam about who was actually behind the murders, the government actually listens to him and puts him in charge of neutralizing the Upside Down and Hawkins. This also results in El and Kali becoming free and legitimized
Kali and El train as much as they can in preparation to face Vecna. The Crawls still happen with Nancy heading them since Hopper is dead. Since the military isn't hunting them anymore, El and Kali go with her. They keep this operation separate from the lab/military since a) they still don't trust them and b) they don't want to trip Vecna or the MF off
Dustin isn't struggling as much since Mike was with him when Eddie died. They get closer in their shared grief, so Dustin is the first to notice that Mike's been acting off
We would get into Henry's backstory a lot more. Basically everything covered from The First Shadow and his relationships with El and Kali. The implication here is that he's convinced himself that he was in control as a way to cope, but he was not much more in control of himself than Billy and Will
Every connection between Henry and Will is forgone. Will's connection is directly to the MF and the s5 scenes of him in the Upside Down don't exist
The day that the Crawl happens and the MF becomes active, Will feels it. He doesn't know what's going on fully, but he's able to sense that Mike is the target. He tries to call and gets through to Scott, but it's too late
The attack on the Wheeler House still happens, but it's to draw Mike there. He's the one taken by the Demogorgon and trapped in Vecna's mind while Karen, Ted, and Holly are in the hospital
Fortunately, Mike is intercepted by Max who gets him to the cave where Henry can't reach them. This protects Mike from the MF's influence as well
El is ready to storm the Upside Down to get Mike back, but Lucas points out that the timing is all too convenient. Kali suspects that this whole time, El's been the true target due to her ability to open and close the gates. If the MF had control of her, it could open a gate anywhere whenever it wanted and take over the world. Her mind's too resilient to manipulate, so they're using Mike to lure her to them
Note that the UD is not a bridge, it's still a parallel dimension. The MF is still trying to merge them but more in the sense that it wants to be able to fully manifest on Earth
Max and Mike regroup in the caves. She tells him about all the horrors she's seen in Vecna's mind. Mike assumes there has to be a way out and decides to explore himself. He sees the horrors firsthand. But unlike Max, he notices how often past images of El show up. He quickly figures out that the MF is after her
That's the final straw for Mike. He thinks about how they've all suffered from Vecna and the Upside Down. How El had to witness her siblings slaughtered and was tormented, how Will was taken, how Max was attacked, how his family is laying in the hospital. He's filled with anger and determination. He finds the exit point in Vecna's mind and gets Max to it. She explains that the opening will only work for her, but Mike is well aware. He practically pushes her to it, staying behind to find Vecna's weakness despite Max's protests
Max wakes up same as in canon, explaining what Mike's doing
El and Kali devise a plan. El will infiltrate Vecna's mind with Kali there for assistance. Meanwhile Nancy and the others will try to find Mike's physical body. El and Kali go in and find Mike with Kali able to trick Henry temporarily while they get Mike to the cave
Mike reveals what he found; the MF has been using Henry as a pawn. It turned him against his family and friends by convincing him they were his enemies and had been using him. Once it gets El, it's going to discard Henry and replace him with her. Mike's plan is to get Henry to see that
El lures Henry near the caves, engaging him in battle. The two of them are about evenly matched due to Kali's training. When El gets the slight upper hand, Kali steps in and conjures an illusion of the MF throwing Henry away once El's in his grasp. Henry doesn't want to believe it, but Mike steps out and gestures to the cave, telling him to see for himself
Henry eventually goes inside, forcing himself through the pain and trauma. And he sees everything, the MF poisoning him against his family, how it's always been the MF who had an interest in El. He realizes that it's true
Henry's anger and realization is so strong that it forces everyone out of his mind. Mike wakes up to find his body with the others as they fight off the MF. El and Kali make it to them in time to see Vecna turn on the MF. Henry spares El and Kali a look and orders them to leave
They do, leaving Henry to fend off the MF while they detonate the Upside Down, erasing the threat it posed for good
The epilogue ends with the graduation like in canon. Only El is there, graduating with her friends while Will attends as a guest. The Party plays one last DnD round, where the Paladin breaks free from his confinement and helps the Mage and her sister turn Vecna against the Mind Flayer. The Paladin and the Mage retire, the Paladin becoming a renown storyteller and the Mage becoming a magic teacher. In reality, Mike and El move to Iceland after graduation where Mike becomes an author and El becomes a school teacher
This is everything in my brain. I skipped over a lot but this is the general plot I've been working with
