Do you find that what excites you changes according to your partner?

[Ozme52]

What's a little disturbing to me is how easily I can shift my own sense of what's erotic, to the extent that my own stories and fantasies change according to my partner's preference. It's almost like the other erotic experiences have been erased. I had thought that I pretty much knew what excited me, but now I wonder if ANY of this actually excites me in itself, or if my own sense of the erotic is just another variable in pleasing my partner.

Sounds to me like you are indeed most excited by the act of providing pleasure...

I've made this sound very black and white, and of course it's not - all of this falls into a context of power exchange and submission, which is why I'm posting here, and of course I would not be turned on by, say, a bottle cap fetish no matter how much it pleased my partner, but within these general parameters, I am troubled by how malleable my preferences seem to be.

This strikes me as one of those things best left under analyzed. In other words, don't be troubled by it. What difference does it make what your preferences are so long as you enjoy them at said time.

So here's what I'm afraid of, and I've been trying for a long time to figure out how to ask about it - If you really like to please another person, how can you tell what YOU want, and not what you want to want because it would please him? How can you tell what's pushing limits and expanding horizons, and what's a sick willingness to go along with anything?

I'll go out on the proverbial limb and suggest that the act of asking the question alone means you shouldn't be worried... and that there is nothing "sick" about it.

I wish I could ask this more clearly. It has been bothering me ever since I found that the act of acquiescing in something that I had previously found unappealing was itself very exciting.

Many do. And shall continue as they grow... as you grow. There is nothing wrong with being excited by what you do, regardless of how you got to that point, so long as it is ultimately consensual.