Hyouzou, would the Mythical Zoan - Batto Batto no Mi, Model: Vampire be an open fruit for use? Since I made that character from the last OP RP and didn't get to use her, I might has well retool her.
I'm not sure. Looking at the CS - and forgive me if I'm being blunt / disrespectful - it doesn't feel at all like a Devil Fruit. Manipulating blood is a little too gorey and might as well be a blood blood fruit at that point with the manipulation. I'll let you use Vampire as a theme, but shouldn't it be a human fruit then? And maybe have more vampirey characteristics, like turning others into vampires, or being unable to be killed unless stabbed through the heart? I'm also thinking the Zoan transformation aspects of it should be a lot clearer, like human -> Vampire human -> Huge bat creature, or make it human -> human vampire -> Scary vampire creature (not just teeth and claws and stuff, but like, really exaggerated and not as human-like to make it clearer). Going from human -> human with sharp teeth -> human with sharper teeth is a little to "meh" for a Zoan transformation. I'll give you the ability to do whatever, though, once you get that partial Zoan transformation thing that Kaido's people and Marco has.
I have a -spoiler alert- Bat/vampire themed character that will be introduced pretty early on (maybe the first island, definitely at least the second one) and be a pretty major opponent that would pretty heavily conflict with your character's theme, but I guess if you really want that one it should take priority over an NPC.
Again, sorry if that was too critical or harsh. I just can't get into One Piece if the characters don't feel like they belong there.