In “The Upside Down”, the final episode of the first season of Stranger Things, the monster attacks our heroes and a group of ill-intentioned adults as they stand in a hallway at Hawkins Middle School. The attack is presaged by an electrical interruption — the lights flicker. Seeing this, Mike looks to the bodies on the floor of a group of people recently killed by his friend, Eleven, and says “blood!” He understands that the monster is coming, drawn by the blood seeping from the corpses.
We know that other characters in the show (Nancy and Jonathan) have come to the same conclusion — that the monster seeks blood — but they had more evidence and made an analogy to sharks. How did Mike know about this trait of the monster? Did they share their conclusion with him? Had he previously figured it out on his own? Was he figuring it out only now? And if so, on the basis of what evidence?