I read Harry Potter and the Philosopher's Stone again recently and the moment in that book that always sends a shiver down my spine is when (SPOILER ALERT!!!!) the seemingly bumbling and nervous Professor Quirrell removes his turban to reveal the face of Lord Voldemort protruding out of the back of his head. I remember when the 2001 film adaptation was released and being somewhat disappointed when I saw the scene as I thought the CGI used to make Voldemort/Quirrell was a tad on the pony side, especially when compared to the other visual effects that were used in the later films.
When I started on the picture I began with drawing a basic outline of Quirrell's head and neck and then added Voldemort later. Because I wanted to show Voldemort with his mouth open, teeth bared and tongue protruding forth, this meant that his lower jaw didn't match up with the back of Quirrell's neck, but I felt it added an unsettling, disjointed look that helps with the tone of the piece. When I was working on the Quirrell half, I tried to make his face pale and haggard and almost old before his time, to show the physical effects of sharing his body with Lord Voldemort.
Harry Potter written and created by J.K ROWLING