Nope, we're going to talk about heroines. In case you're wondering that falls under the category of characterization. I have a beta reader, a live one not a muse, who is great at predicting what story is potentially great but also honest enough to tell me when I'm getting repetitive. When I hear the "r" word, I freak. Usually she is referring to my "style" so I can calm down a little since mine is a bit on the different side.
Still I have that other girl, the muse girl, sitting on the right or left shoulder, her choice, tugging on my earrings to make me step back and look at my main female characters. I dread the thought of using a mental cookie cutter to create them and so I'm constantly on the lookout for anything repetitive. And so is she.
How do you create heroines that differ from one other? Well, first and most simply, the physical description. I've had a character tall and powerful and brunette as well as two petite ones with black and blonde hair. That's the easy way out. But it's also the opportunity to layer that character a little too. Do their physical attributes affect their view of life? For my work, that's most of the time. My tall and strong heroine, Khai Zafara, from Inamorata Crossing, never thinks about it. She's a dedicated soldier at least at the start and takes her physicality for granted; for her it's a positive attribute.
Payce Halligan and Isadora DayStar are both small and petite; one blonde, the other black haired. One ignores her size until it becomes a problem and then she responds with feistiness. The other sees herself as a tiny person in her universe, her worth even less than her size. But that's the superficial layer.
It's the deeper layers that truly differentiate characters. How they respond to themselves and their conflicts is the key here. Anger, revenge, fear are some of the conflicts characters have to and should be dealing with in their stories. But there's one other conflict that many authors don't include. I've said this before, a bazillion times: guilt is a powerful motivator. Not only that but it's a fairly common motivator for readers as well. In other words, guilt is also a fairly universal experience. I give my characters a ten foot duffle bag of it to drag around.
How each character deals with it is the conflict. It's the major differentiation between female characters. To give you an example let's look at Payce and Isadora again. Both Payce and Isadora have major guilt over almost the same thing but on different scales. Payce deals with it by withdrawal and obsessive target practice as if reliving the trauma over and over and attempting to recreate it with the right outcome each time. Yes, I know that sounds like the recipe for insanity, but it isn't. She isn't so obsessive that she can't function—she uses target practice also as a form of self-therapy—to make sure she doesn't make the same mistake again.
Isadora on the other hand, tries to bury her past to the point of desperate addiction to kill her memories and her guilt and any emotions attached to them. To that end she debases herself completely and horrifyingly for the drug, thereby confirming, consciously and subconsciously, that she has no real worth whatsoever. Her guilt overwhelms her and just surviving becomes a suicidal struggle.