It's a cross between Harley Quinn and Fiona, but I'll go with Harley Quinn. Fiona's costume might be more easier to assemble and relatively cheaper, but if you want to go all out, Harley Quinn is the best choice. You're going to be evil-ly beautiful in it.
@ Grump Bunny Aw thank you Right now Harley and Witch are both winning, Fionna is second and Loki is last! But I do have a few months so I guess I'm preparing early
Harley Quinn! I think you would make a drop dead sexy Harley Quinn. but it looks like it would be tons of fun, even though it would be expensive. Witch is my second favorite, I mean, like you said badass as hell, even if people wouldn't get it. But I could totally see you going as Fionna the Human, because it would be fun, and you are a super fun person. Best of luck!
But of course!