Chapter Text
The story starts very similarly to the start of season 3, with a few key differences. Starcourt Mall is built where Hawkins Lab used to be, and Billy was kicked out by his father after he failed to bring back Max at the end of season 2. Nancy has been investigating the construction of Starcourt Mall, believing its construction to be suspicious, but her bosses ignore her and put her down similar to in the show. Dustin doesn't intercept any Russian transmissions since Russians aren't a thing here, but he does hear some weird noise that he decides to ignore or doesn't hear, which foreshadows the return of the Upside Down. He now lives in the trailer park. Max feels really guilty about what happened to him and has been trying to build a relationship with him ever since, but he shuts her out. Also, in between seasons, Hopper tries to give custody of Eleven to Joyce, believing Eleven would have a more normal life with Joyce, but she assures him that he will be a good father but they do decide to come up with a co-parenting situation for Eleven. This forms the basis of their romantic relationship.
Also, Hopper isn't an angry asshole like he is in season 3, and his character is similar to what it was at the end of season 2. He still disapproves of Mike, but he doesn't straight-up threaten him. Mike also has an underlying resentment for Hopper because of Hopper hiding El in season 2. He chooses to avoid going to El's house because of Hopper's constant surveillance and interruptions. Everything else is pretty much the same. El goes to Max with her relationship troubles, they go to the mall and become close friends, El dumps Mike, and Will tries to set up a DnD game. Also, Dustin is there with the boys the whole time. After this point, things are COMPLETELY different.
Will destroys Castle Buyers, similar to in the show, but instead of Lucas and Mike, he is found by Jonathan. Instead of being mad like Will expects, Jonathan kinda takes the blame for Will's loneliness, affirming to Will that he would be a better brother. Their conversation is similar to the one they had in Season 4. Will pseudo-comes out to Jonathan, not explicitly stating he is gay, but saying how he feels different and left behind by the other boys because he doesn't like girls and is afraid he will always be different and left out because of his experiences. Jonathan is supportive of him and manages to talk him down, and both of them decide to build a new Castle Buyers which would reflect Will's growth more.
When the two come out to build the castle the next day, they find that Lucas, Dustin, and Mike are already trying rebuild it. The three of them apologize to Will, feeling guilty after reading the campaign he made and seeing how fun and detailed it was. Will decides to forgive them, and they all start building the castle together. During the building, Will starts to feel extremely uneasy and has flashes of the Upside Down. He then gets irrationally angry at a very small problem, lashes out at everyone, and storms back home. Joyce notices him coming back to the house angrily and tries to talk to him, but he angrily shouts at her too, before going to his room. Jonathan also comes home following Will and explains what happened.
Joyce goes into Will's room, but instead of trying to talk to him, she immediately sedates him, believing that Will would not act like that with her under any circumstances, and believes that something related to the Upside Down may be going on. She then decides to call Hopper to figure out what to do. Jonathan tries to explain to Joyce that Will's behavior may be because of his sexuality(without explicitly outing him, of course), but Joyce implies that she already knows about it and still believes something else is going on. Jonathan chooses to believe her after this. Mike, Dustin, and Lucas are still skeptical, although does feel reminded of how Will acted when he was infected. Hopper shows up, and although skeptical at first, he chooses to believe Joyce since her intuition has never been wrong. They decide the best way to test Joyce's theory is to expose Will to heat and see how he reacts.
Meanwhile, Max and El have plans to meet up at the mall. On her way there, Max decides to make one final attempt to talk to Billy, knocking on his door. Just as she is about to leave, Billy opens the door and greets her warmly, letting her inside. This leads to Max being late for her meet-up with Eleven, who decides to explore the mall alone and seems to disappear. Max, after spending some time with Billy, who seems much nicer than he was previously, goes to the mall to find Eleven missing. Believing she went home, Max goes to her house to apologize, only to find her not there. Max then looks for Eleven at other places she may be, finally reaching the Buyer household. Just as she explains what happened to Hopper and Joyce, they hear a scream from inside the house. Will is having an adverse reaction to heat, indicating that the Mind Flayer is, in fact, back and may have something to do with Eleven's disappearance.