Well, in a way, I think she fulfills a role where... huh. Too long to write right now, but a brilliant creation (Thank you, Dennis O'Neil) and a definite 'other woman' versus 'the real one' who is Selina. IMO.
Heh on Sherlock Holmes and 'The Woman'. Except I always felt like Holmes never had sex and I think Batman has sex sorry, 'makes love' two or three times a year.