I'm still unsure about the background, but these last two days I've been having fun drawing with Posca pens on this painting, and I love the result.
I painted this many years ago, probably about six, and it was just the skull with its tongue and red glow. I never touched it again, and it was in a room covered in dust. Two days ago, I needed to get away from the computer and use my hands. I remembered this half-finished painting and started drawing on top of it.