If that's too complex, something where felix is sitting cross-legged and has YumiYu in his lap would be cute too. Your choice.
With either one, maybe have Felix's guitar laying beside them?
And background is your choice if you wanna add one.
YumiYu: The little android girl
Felix: The guitar-playing flirt
Note that Yumi is a halfkin, so she'd be smaller than Felix.
EDIT: Apparently I'll be paying instead of Yumi, and when it's done. Ha ha, okay.