okay basing this little Post on that thing i reblogged earlier about will + paradox shenanigans. so here’s some context behind that (note: there are some inconsistencies here that i have yet to work out, mostly with the flickering lights, timeline, and demogorgon shenanigans but. yk):
basically, i think will was kidnapped by vecna on november 6th; vecna did not want to kill him, no, he wanted to convince will to join him because will was more powerful than him and truthfully? vecna was terrified of him. more on that. later.
so will gets kidnapped. he evades vecna for a while, and then...brenner sends his men in to take will from vecna. i don’t have a clear picture of this yet, but something something they went through the gate in hawkins lab something something brenner knows about will’s powers something something fake body something-
anyway brenner takes will in. will does not like this. he wants to go home. however, brenner, knowing will is different than his other test subjects, decides to treat will with care. he feeds will and cleans his wounds. he essentially let’s him “crash” at hawkins lab. will just wants to go home. obviously
but then. then brenner says he wants to try experimenting on will (hence the faked death). obviously, that’s a no. will does not want to be experimented on. he wants to go home and see his mom and brother, who are worried sick. so will runs. and that’s where vecna comes in.
vecna possibly? emerges from the gate already in hawkins lab at the time. and then something something vecna and brenner fighting over will something something powers something something brenner once again proves he Cannot Die. something something. will runs back through the ud gate to escape. vecna chases him.
will runs into the upside down, evading vecna, who atp is So Done. will hides. he doesn’t know why people think he’s “special”; he doesn’t know why brenner wanted to experiment on him, why it was him who vecna took. he doesn’t know. he’s 12, and he’s confused. and scared. he has powers at this point, yes. but they aren’t activated.
vecna is drawing closer, and will is running out of time. he figures, okay. i’m going to die here. but then. okay. this is where the paradox stuff comes in.
older!will, who has entered the upside down because of the apocalypse and somehow wandered into this scenario, realizes that what he’s watching unfold happened to him. and as vecna draws closer, older!will realizes something: he was able to activate his powers because of...himself. so, even though older!will knows this is a bad idea, that it would mess with the timeline - but wait. no it wouldn’t, because vecna erased his memories. he didn’t want will remembering this.
so older!will takes the opportunity; he runs to his younger self, and he gives himself some words of encouragement. because at this point, older!will knows he has powers. they were activated again during present day by some other means. and it’s older!will’s words that activate younger!will’s powers - again a lot of missing pieces here, i know - and subsequently, younger!will blasts vecna into oblivion (almost).
older!will escapes from there. younger!will is then taken by (a very beaten up) vecna into the library and has a vine stuck down his throat so vecna can study and sedate him.
and that’s why it took so long for vecna to come back to full power; will byers had almost obliterated him.
notes:
i’ve also seen a post by @/will80sbyers about how the ud being stuck in 1983 may just be a “snapshot” - like a pocket of the upside down that’s stuck, while the rest of it has normally flowing time (i don’t remember the specifics, but it was something like that). i actually am onboard with this theory, considering it would explain why older!will would be able to wander into younger!will’s fight with vecna back in 1983 without disturbing anything else by fighting within the upside down during present day.
does this make sense??? im so sorry if this isn’t coherent. it is Very late and i need sleep. lol. btw i kind of have a fic concerning this topic...in the works??? kind of??? i need to work out the exact timeline and rewatch s1 and s4 for it to work but. yeah. anyways!!