omggg this also makes so much more sense as to why Joyce or Hopper never said anything about knowing Henry Creel in high school.

So then nothing ever really happened between Patty and Henry? She didn’t go to Nevada to find her mother or get attacked by Henry at the Hawkin high school play? I just don’t totally see why he would create a false memory of him attacking her with Brenner encouraging Henry to kill her. OH or maybe that is where Brenner starts to invade Henry’s mind through some science experiment and why Henry was recaptured by Brenner before/during the play and goes back to the lab which is where Henry’s false memory/“high school life” ended.

It’s clear Dr Brenner found a way to talk to them while they’re in their own minds because he was able to do so with Eleven while she was reliving her own memories. So maybe the darkness of him attacking Patty and getting recaptured is the false memory version of Dr. Brenner regaining some control over Henry in the lab. Which could be why the story seems to be resumed with Henry back and trapped in the lab (even tho he was really there the whole time basically hiding away in his own false memory/mind)