Both The Harry Potter franchise and Stranger Things star a group of rather unique young kids who are each trying to solve a mystery with or without magic or special powers. Putting all these kids together in various shared scenes really works well.
Outcasts Mike, Dustin, and Lucas fit right in with Harry, Ron, and Hermione in the Great Hall of Hogwarts as Professor Dumbledore welcomes everyone. They even team up and take down the bullies who repeatedly pick on Will when Hermione (in place of Eleven) breaks some poor kids arm with a swift flick of her wand.
Hagrid warns that there is a storm coming, and they all best be ready when she does. The "storm" ends up being a scared weirdo named Eleven standing outside in the rain, to which scaredy-pants Ron squeels, "Harry!"
Alan Rickman even makes an appearance as his beloved character Serverus Snape in place of Benny the diner guy to warn Eleven not to steal or else he'll add a little something extra to her morning "pumpkin juice." Too bad she likes Eggos, Snape!
It gets real weird at the end with the theme songs from both Harry Potter and Stranger Things are combine to create a terrifying noise that sends a shiver down or spines.
While the mashup is certainly fun, this does pose a larger question - Will Stranger Things become as popular as Harry Potter? The Duffer Brothers, showrunners, already have multiple seasons planned that will follow the Harry Potter model, meaning each new season will most likely start at the beginning of a new school year.
Both franchises incorporate kids, magic, mysticism and a dark side, whether that's The Upside Down or Voldemort. Either way, we are desperate for more of each!