I have no idea how I found this subreddit or thread, but I went to high school with him. He was super normal. Never gave off any weird vibes (no weirder than any other high school kid) and was a really talented musician. He introduced me to a lot of the bands that I still love to this day (mostly pop punk). The change happened after high school. He was a few grades ahead of me so once he left high school, we lost touch. I remember hearing that he went to hair school, which was a super drastic change to the person he was in high school, and then started dressing how he dressed in that band. Nothing out of the ordinary initially.

*added bonus info* In high school he was in a band with one of the founding members of Sleeping With Sirens