By far the biggest surprise.
I know - it's amazing how he grows on you. He's got the best "villain" part of the whole show, I like what they are doing with him.
I don't know much about the Bat universe, but I like the potential behind the idea of the singer being Harley Quinn - not so much as being accurate, but I think that her presence on the show could be the "Joker" element. Gotham clearly plays fast and loose with the timline, so maybe...
Any other suggestions who the singer might turn out to be? Or maybe she's just a creation of the show - Fish Mooney is exclusive to the show, right? She doesn't exist in the comics does she?
Would be amazeballs if they reveal the singer to be Harley. Harley hasn't been in any non-animated TV show/movie right???
Looks like the actress is Makenzie Leigh...although virtually no info about her online.
With it's current timeline, the singer being Harley would be way off. Bruce and Selina are kids now, and I've always thought of Harley Quinn to be much younger than those two.
She was in Arrow.