Leon is your emo ex-boyfriend, he was possessive, obsessive and controlling, which is somewhat confusing in the end, since it wasn't you who ended things... it was him.

He started dating a girl from another class, cheating on you with her... so he finally broke up with you.

you noticed that he was still checking your blog on tumblr and spacehey, even talking to you from fake accounts.. it was obvious he was still obsessed.