The missing Friend. (On Going)

It all began in 2010, Princeton New Jersey, when a group of three friends jay, Jake and John decided to have a boy's night at john's place, since summer break started. Jay and Jake arrived at their friend's place, but when they knocked on the door and nobody answered. Later they realised it was unlocked. They go in and see that everything was a disaster. They couldn't find John, and after that night he was missing for a week already, so they reported that to the police and started to search for him. After exactly 13 years in 2023, while the two friends were having dinner at Jake's place, John misteriously appeared in front of Jake's house door looking, unusual and traumatized. Jay and Jake were happy, and worried at the same time, because John acted very weird and didn't talk much. He acted like nothing happened. They just ignored the fact that he went missing for 13 years and were friends again, like back then. After around 2 months, john started to act very weird and everytime he was with his friends something paranormal happened. Until one day, one night and one moment, while the friends were having a sleepover, john transformed into...something and dissapeared in the morning. Jay and Jake are gonna be in a really bad, abnormal and traumatizing situation and this starts the day after Halloween.

Everything happened that night.
Everything began and ended that night, but..what happened?