why not bring the whole gang

I always wonder when everyone decides to tell Max about Eleven. 
I imagine after a few months, they had to. She would always ask about Will, and why Mike was so emotional about a number. The boys had a huge meeting before, they spent nearly 2 hours discussing whether to tell her or not, how to tell her, and Will spent the time drawing some of the scenes for reference. They set aside a whole evening, and bring as many blankets and pillows as possible. At first Max is weirded out and a little uncomfortable by how serious the situation. But after everyone settles down, and snacks are evenly distributed, Mike begins. They all tell the pieces they remember the most. Will talks about the Upside down, Dustin talks about getting chased by Troy, Lucas tells of his mission to spy on the lab, and Mike chokes up everytime he mentions El. When they finish, no words are said, but a few tissues are passed around before they silently roll out sleeping bags and retire. 
Max understands now. 

The Black Arms have been low-key mind controlling Shadow since the beginning, though it only extended as far as altering his thought process and memories ever so slightly. That is why he had amnesia and why Sonic and the gang seemingly never tried to explain who he is, when they were actually doing that the whole time. The Black Arms make some small changes, and everything the gang brings up about Shadow’s past is rendered as babbling nonsense and thus goes blatantly ignored. It was all done in an attempt to gain Shadow’s loyalty to the Arms, seeing as nobody else can help him, even though everyone’s actually desperately trying to.