In just three seasons, Stranger Things has built its own mythology, but it has also left behind many mysteries that viewers hope will be answered one day, and most of them are related to the Upside Down.
Will is the only person in Stranger Things known to have survived several days in the Upside Down, but what makes his experience even more interesting and intriguing is that he was able to communicate with his mother by manipulating the lights in her house.
The Byers’ house appeared as it was when Will disappeared, which means that the Christmas lights and the alphabet never appeared in the Upside Down version, so how could Will manipulate them to communicate with Joyce in Stranger Things?
Some theories suggest that Will has powers of his own that he hasn’t really explored yet, and these could be psychic abilities. With that in mind, Will would have “activated” a form of communication with the human world in Stranger Things.
Others suggest that Will, Joyce, and Jonathan have psychic powers, some more than others, as Jonathan recognized Joyce in all dimensions when he entered the Upside Down to rescue Will in Stranger Things.
Another slightly simpler explanation is that anyone who walks through the door becomes magnetized in Stranger Things. It is explained at some point that the gate would have a strong magnetic field, so it is possible that anyone who crosses it is affected by it