They should kick ass but have other talents; they shouldn’t necessarily kick ass because that’s been done to death; they should have agency; they should move the plot forward; they should be assertive but not obnoxious; they should hold positions of power; they shouldn’t be raped or die to give the hero incentive for his quest.
What I think is missing from some of these discussions is: writing a fully realized character of any gender requires one trait above all others, and that is empathy. When a female character goes off the rails, it is often because the author experienced a failure of imagination; while he could imagine all the emotions a man might feel in a similar situation—and
in the case of literary fiction written by men, this is often recounted in great detail—he has neglected to understand his female characters in the same way. Instead there is a hyperawareness of her beauty and sexiness even from her own perspective, such as in Jeffrey Eugenides’ The Marriage Plot; an inability to grasp how the character might experience life from the inside. I think when male authors make this mistake it’s because they forget we don’t see ourselves the way they see us. I don’t want to go so far as to call this a lack of empathy, but it is certainly a failure of imagination.
And my personal favorite:
How about this: if writing a female character is difficult for you, try forgetting the character is a woman unless the fact is somehow relevant to the story. Heck, even if it is relevant, forget they’re a woman—or perhaps it’s more accurate to say, forget what you think you know about women.
Get into your character’s head. Forget about her body unless another character is looking at it. Forget any assumptions about what women are like. Let her surprise you. That ends up being a double win—for the reader and for you.
There are very few male authors that I will read and not cringe with their female characters. I usually prefer to read books written by authors who share my gender and her are empathetic with me by default. For those few male authors who succeed in the well written female character (strong or otherwise), I will return to their other and future books loyally.