I just read a few days ago that the song "Possession" by Sarah McLachlan was actually based on a letter written to her by a very obsessive fan.

It kinda changes the song's perspective... but it's still fucking cool.

I usually get scared when I find out that I am about to hear or read the motivation or inspiration for a song. So often, I attribute my own back story to a song, making so much cooler than what I eventually hear the actual meaning was.
Not in this case, however. That history is actually much much cooler than the failed highschool or college crush I'd imagine she wrote about.