Seeing as the two Harry Potter headcanon pages I found are inactive, I've decided to create a new one myself. 

nightlockpills:

It is a part of the Harry Potter confessions blog Chelsea and I run, therefore, Chelsea has control over it as well.
It’s as simple as the confessions. Send in your headcanon to the ask box or submit your own graphic and we’ll post it.

(Source: morilocki)