What ideas did you have for it? Is it two girls? What type of characters do you like to play? As a guy or a girl?
Two girls, so I would be playing a girl, of course. Preferably The one with Purple hair.
As for ideas, I'm not sure....The picture is of a Yuki-Onna (Or Snow/Ice Demon) and a Succubus, so I was thinking maybe a monster-girl highschool or even an adventure that has brought the two together.