Problem fixed.
I thought about bout how some materials, like Bones Miniatures, don't take well to priming. The way my paint was acting reminded me somewhat of when I recently started painting a Bones mini, and found out after priming that they actually aren't supposed to be prepped in this way. So I took the ingenious measure of painting on the plasticard side that was not primed and TAH DUH!!! No I haven't tried anything too fancy on it yet, but it just seems like it is acting right.
So I guess I'll just base coat it with my background color and start to free handing. If the result is not too embarrassing, I'll post it here and my WIP so everyone can see how well a talentless hack like myself takes to complex freehand design.