Iphtiny
Billy Hargrove died. At least, that's what everyone believed. But somehow, he survived. He built himself a home in a world where the sun never shines. He learned to live among monsters. He lost his fear, his purpose, his sight and, eventually, himself. When he finally returns, Hawkins no longer feels real. And the man rescued from the Upside Down is no longer certain he still is one. What makes a person human when everything that once defined them was left behind on the other side?
Or: After escaping the Mindflayer's control following the sauna test, Billy becomes trapped in the Upside Down. There, he uncovers the truth about Hawkins, his sister, life and death, and how frighteningly easy it is to forget the real world. If he ever makes it back, he'll have to learn how to live among people all over again.