My characters and I exactly alike? Sheeyeah. I wish. Especially on the physical abilities side. Clearly not the case. Ari, Jay and the newest heroine, Cashel, are all super fit fighting machines. Me? I'm a gimp. This is writing at it's Freudian Wish Fulfillment best.
But let's delve into the concept of aspects - this is the notion that you aren't just one thing. Each of us is a conglomerate of a number of aspects. Think of a diamond with multiple facets. Each of those facets represents one of your aspects - a different face you present to the world and to yourself. Mother, daughter, sister, wife, business woman, writer, athlete, etc. On a diamond, facets reflect and refract light so the diamond sparkles. In humans, our aspects reflect and refract reality through our perceptions (there's some theory that we focus consensual reality via our perceptions - but that's topic for another day). Suppose you have a fender bender. How you filter that experience is likely to be different based on whether you have your newborn in the car or your boss.
The point to the aspects explanation is that every single character in my stories comes from some aspect of myself. This is necessary - my emotional processing is the only emotional processing system I know. I can imagine I know what someone else is feeling, but really, I don't - I can only relate someone else's anger to my own anger. When it comes to feeling things, each of us really is the center of our own universe. So while I try to make each character into his or her own unique individual, the only emotional reference point I have is myself and what I can imagine *I* would do if I had x background and found myself in y situation. Oh, look. The acting degree in action.
Does this include my alien badguys as well? Yes. The torture scenes? The terrible things people say and do to one another? Completely. I subscribe to the school of thought that suggests we cannot claim the fullness of ourselves as humans unless we're willing to acknowledge and embrace our shadow selves as well as our socially acceptable, sunshiny selves. The human animal is capable of awful things. It's therapeutic, mining that for story material. Though it should be noted that most bad guys aren't bad because they want to be - they're doing what they do for a good-to-them reason.
Regardless. My heroes and heroines - if we really want to be specific - they are what I wish I could be. Pieces of who I'd like to become. In every story I do, I think there's one thing all my heroines have in common - they start out alienated and isolated. Most of them are searching for a place to belong. I think that defined a good portion of my life until I found my fellow writers. In that aspect, my heroines are, in fact, me.