And I don't think it's possible to avoid the Mary Sue label with a female OC of any importance. *checks* Okay, not true, Elizabeth Phelan didn't get any reviews to that effect. But it really does seem that way sometimes.

I have a lot of issues with that. I mean, I'll admit I think that there ARE a great many fics that are written where the OC and Harry just... take off in the sunset, and Ron, Hermione, and Voldemort don't exist because Harry and said OC are snogging and that's all there is. But you're right, there's plenty of authors who have been able to do it well, such as Fern Withy with Elizabeth Phelan.