In S06E10 of Arrow, there were two scenes where black siren was shown and she had entirely different hairstyles. In one scene her hair was short and black whereas in another scene it was long and blond.How does her hair grow so fast and the hairstyle changes?
I think, if you pay close attention to when she wears the black wig and when she doesn't, she only seems to wear the wig when she is doing underhanded shady stuff with Diaz. When she is around Quinten and the others, she doesn't wear the wig. It's all a part of keeping her cover.