In Batman #7 we see Batman rescued by a girl who calls herself "Harper". It's implied that Batman and her had endountered each other before (see the comic panels below). What has she appeared in before, for them to have run into eqch other?
Well, isn't it revealed in issue #12 Ghost in the Machine?
I will not spoil the comic issue itself, but here is the second encounter with Batman. The first one seen also in this issue is briefly through Bruce in his own house (no spoilers).
After Harper and her brother are rescued by the Bat, she develops an obsession for Batman. She finds a way to track him through the city, and secretly helps him. His first words to her are "Whatever you think you're doing, you're finished." At this point, I don't think the Bat knows he has helped her before, seen in the comic panels above.
As far as I can tell she is going to be quite important in the future issues of this series. She could be someone important or closely related to some important figure in Gotham's past, or to Batman himself (I secretly hope it's Barbara Gordon / Batgirl / Oracle).
Who she really is, only future issues will reveal.
Her name is Harper Row. It is implied in their brief interaction that Harper and Batman know each other, but Batman #7 was the first appearance of the character, so readers know nothing about her at that point. Here's what writer Scott Snyder had to say about her in a recent interview:
Harper Row is her name and she's a character I've been thinking about for some time. I don't want to give too much away, but you'll be seeing more of her in Gotham soon - she has an important role to play in upcoming stories.