This process mostly demonstrates my normal working process: I started with a really rough, basic sketch. Then I fleshed it out and made some finished looking linework.
Next, I added the color flats. With these, I just put them down in any color and then use the Hue/Saturation adjustments tool to change them later. This process included the addition of shadows (a semi-transparent layer).
And then came my favorite part...layering on the texture!
For a little while, I thought I was done. However, upon going back and re-examining it, I felt that I wanted a whole lot more context. The story's main characters are not just Horace and the firefighter; there is a third character - the fire. So I decided to rework the composition to include more fire, and more destruction.
There. Now I'm satisfied. I removed the shadows, thickened the linework on Horace and the firefighter, and added a whole mess of fire and melting buildings. It's a shame that so much of the time I spent investing into the details on the two people didn't appear in the final product (the shadows, the tiny wrinkles and buttons, etc), but that's just part of the process.