I ended up working into this more with colored pencil than marker- I still don't really trust myself to pull out soft shading with prismacolors, though my small collection of greys are subtle enough that I trust them a bit more. I've been slowly training myself to work up to dark colors slowly and lay in the quiet shading first.
Cleaned it up a bit in Gimp and put in that cloudy effect around the top of the image. Not exactly the glossy effect I'd really like to achieve someday, but at least I got some practice in.
Art production and focus has a direct correlation to my mental state, which has been set to "off" and "down" lately, for a variety of reasons. Paper and markers continue to be cheaper than therapy.