New Nightmare Fuel.
thanks a lot.
1. FlutterHulk is good. If you wanted to add a bit of "cheesecake" factor, you could "dress" here in a ripped-up bikini-style, a la She-Hulk style during Jennifer Walters' early years. I might suggest re-coloring FlutterHulk's clothing more towards her costume coloring as Saddle Rager. As I have remarked, detailing with Source Accuracy is a strong fan-artwork tool & factor.
2. FlutterBat, I rather dislike. The whole "lamprey vampire mutants" of Blade II made me /facepalm (even saying it makes me ), and that was not counting the already weak nature of the movie itself too, because the writers could not come up with a good Nosferatu-vampire horror-inducing variant.
3. An alternate suggestion... I think it might be better if FlutterBat were still mostly human, but with according vampire bat features (a la episode canon) such as bat-wings, elongated ears, and fangs; claws optional.
4. Another alternate suggestion... An alternative, conveniently within comic-book themes, is that you could have FlutterBat more in theme and design to Batman's occasional antagonist, Man-Bat. Which in turn makes for easier writing since you can look-up & draw upon those battles where Batman struggles to stop Man-Bat's rampages, but is also hampered by trying to save him & restore his humanity.