I don't call myself a switch, because 1) that implies a binary where I choose to either be one or the other but I can't merge them, which is not true of my experience, and 2) other people who identify as switches usually do so because they have active, intrinsic desire to be submissive as well as active, intrinsic desire to be dominant. I don't have either of these things.
I call myself an erotic mirror because my access to the erotic is reflective. I don't have much intrinsic desire for sex in general (I am demisexual) and I have zero intrinsic desire for roles in sex. I don't daydream about particular kinds of sex or power play, for instance. I find the idea of imagining sex or power play to be very boring; when I masturbate, it is usually while paying attention to music or just meditating. I don't masturbate out of desire for sex; I do it as a gift to my body, or because I want menstrual cramps to go away, or to be able to fall asleep quickly, or because I want to meditate and can't focus enough without involving my body.
Rather than from within me, my sexual desire comes from an interaction with a person where they have a particular desire and my desire mirrors that: they want to submit and thus I want to make them submit, or they want to take charge and thus I want to allow them (though that is rare because I dislike how most people try to take charge: a person has to have an innate connection with their primal self for that to be appealing). Or if they want me to give them a particular sensation, or want to give me a sensation, then I want to do that too (unless receiving the sensation is actively unpleasant: if I am neutral on it and they want it, then I want it). If they have no particular shape of desire, then my desire is somewhat random -- whatever memory comes up of an occasion that was particularly emotionally intense is what I will want to do.
The only things I really love for their own sake are biting, kissing, and energy play. Even if the other person doesn't have an active desire for these things but is like "they're okay, I like them a little" I will want to do them. Not as much, but at least a little bit. Whereas with other things like genital touch or bondage, if the person feels only mild desire, I won't want to do them any more. I only want those things if the other person is really into it.
This is also why I think there is very little that someone could want me to do to them that I wouldn't want to do. Unless it violated one of my core values or risked serious bodily harm, I would probably be down.
I think I have had sex with one person who was also an erotic mirror, and our sex was so intensely connected that sometimes I wasn't sure which limbs were mine. It was transcendent: the emotional equivalent of two mirrors facing, endless recursion. I'd love to know more people who are erotic mirrors.