These are the initial sketches for Pop and Locke's character designs by James Stowe (of D&D for Dads fame). He offered up many different heads and bodies for each character and was very patient with my photoshoppery fiddling.
These are James' final designs in color. Funny thing, I initially directed James to draw Locke with a fork, but it looked a bit more menacing than I expected. That's why she now carries a spoon. I don't know what the spoon does, though. Meanwhile, Pop has a pencil whose point lights up like a flashlight.
To see how this all started, check out my post on the Pop and Locke Artist Style Guide. That outlines the visual references I first gave to James at the beginning of the art process.