This is something deeper and less clear to me. It's something that I have always thought was very, very strange about myself, but I never had any context to use to even try to figure it out. But it is certainly there, whether I understand it or want it, or not.
I read every moment I could as a child. I much preferred to be immersed in stories others had created than to sit and daydream. When I did have mental free time (I'm old, this was pre-electronic entertainment), if the option was not there to read something, I did daydream. My reveries were likely not as imaginative as many; most often they were merely extensions of whatever make believe world my current novel had created. Very few of my daydreams related at all to my real world. I never imagined growing up, or getting married, or my wedding day, or any of the triumphs that seemed to be important in the world of that age.
But my mind did wander to needles, often. I would recall getting shots - a common enough occurrence for a child that age, I would dwell on it in my mind, the way a child worries a loose tooth with her tongue: it hurts to push it around, it calms to a dull throb if you stop, but that doesn't feel quite right, so you push and twist to make it a more immediate pain. This was what my mind did with needles. I would dwell on the memory of it, and on the idea of it. And the memory and the imagining seemed to be as much in my flesh as in my mind. I was allowed to get my ears pierced for my 10th b-day and I created that scene and reveled in it in my mind for months beforehand.
Even then, I wonderered that, of all the real world things my mind could choose to dwell on, this seemed to be the only thing it did. I was convinced that this all meant that I should be a nurse or doctor when I grew up. Ironically, I went into a health care field which involves no invasive procedures at all. I never did put it together that, in my daydreams, I was receiving, not giving.
I am reluctant to use the word fantasy about this. I was certainly well younger than puberty when this started. Even as I got older and began to incorporate the sexual into daydreaming, I really don't think I put the two together, certainly not explicitly or that I recognized. In fact, the imagining about needles subsided greatly as I moved through my teens, I had always thought that it was replaced by the typical teen obsession with anything sexual. And it probably was.
I don't know how much pre-pubescent day-dreaming is or is not sexual at its root. I am learning that pain is very intertwined with my sexuality, something I would not have imagined a year ago. Reading about the masochist's experience of play has a very distinct effect on me. But the first time I read about needle play, it was like a kick in the gut. It knocked the wind out of me. Memories came flooding back, memories which suddenly had a context. Of course it also had the the effect of being overwhelmingly arousing, and something maybe more that I can't quite put my finger on.