Reed!! I've been thinking on this theory: what if the demogorgon ponders their victims by their fears?. Ex: it killed Barb and she was scared to death like actually terrified (but duh obvs who wouldnt?) and he used Will with the slugs and what not, and yes he was also terrified BUT he confronted the demogorgon and was just this clever boy who knew how to avoid it and distract it. So what if besides blood, he tastes people by their fears?
That’s actually a really cool thought. My personal belief rn (not knowing anything about season 2 basically) is that The Demogorgon is actually a product of Terry Ives’ mind that detached itself from her body (and this all happened because she was experimented on as well and who’s to say she doesn’t have powers just like Eleven) in order to search for her daughter. And the mind spent so long away from her body that it became trapped in the upside down and turned into the monster. So when Eleven is put into the tank (the monster reaches out for her) she opens the gate to the upside down which lets the monster escape.
Basically, I think the monster/Demogorgon is after Eleven. It may or may not be attracted to blood (cause El has her nose bleeds so we don’t know). And I think it can sense loneliness on some level. Barb felt alone, who knows how Will felt.
There’s also the matter of the two hunters that disappear, presumably killed by the Demogorgon as well.