The final concept rendered in photoshop. Lit with a low key setup and rim lighting in mind. As this is a demon I thought about peircing yellow eyes in the night with a blood-soaked grin staring at you. 

This was the base concept I drew in Sketchbook Pro. Symmetry is usually on when I do these so I can get them done quickly and have a consistent shape. I was originally going for a dragon but added more mammalian shapes and gave it bat ears.