I think maybe you have too strong of a focus on plot. It’s there to give structure to the breakdown of a family that is passing down mental, emotional, and supernatural problems like they’re hereditary. It’s a showcase of how a family raised to be tools can devolve when they’re finally being used.
!Personally my favourite part is the massive tone shift at the very end when Peter is finally possessed and receives his revelation. It’s a beautifully crafted scene that balances being celebratory and morbid. A fantastically unique payoff to an entire movie’s worth of buildup.!<
That person that is kind of lacking in social skills, still weirdly opinionated about really specific things, doesn’t care enough about their appearance for how old they are, and several other holdovers from being a nerdy high school shut in, but is very slowly becoming better. They’re trying to understand how to have more flexible conversations with people, figuring out a clothing style that works for them, and just doing some general growing up. They’re still kind of hard to be around, but you can tell they’ve made progress and that’s all you can really ask of them.