I became conscious of my fantasies when I was very little, around 4-5 years old. I thought that it made me "different" somehow but I wasn't isolated: my best friend at the time was a good confidante, and was often giving me a hand whenever I was playfully tickle-assaulting my female classmates in catholic school. Growing up, I spent most of my childhood and teenage keeping a low profile about it. As a matter of fact, I really believe in the "don't ask don't tell" policy: I can do whatever I want in private, but I do not have to shove it into everybody's face.
Thus, I thought that my tickling fantasies made me "different" but not crazy, no. My sadism on the other hand was a little bit worrisome for me since childhood. The inexplicable turn on I was feeling to see a woman tied up, screaming under torture (not necessarily tickling) and begging for mercy was somehow unsettling. And was in deep conflict with the christian morals my school and parents were preaching. As far as I can remember, my childhood heroes were often the bad guys in movies and TV shows. There was a point when I was wondering if I was gonna turn into a criminal or something in my adult life.
Another worry of mine was that vanilla porn was an absolute 0 turn-on for me, save for the odd lesbian sex sprinkled here and there. I was borrowing my friends' magazines to avoid suspicion, but my real "porn" at the time were those crime and spy novels with those interrogation scenes and whatnot. The porn that was airing on TV was a serious turn-off as well.
Both were resolved around 15 when my parents got the Internet. Oh boy! No need to be bothered with some other people's fantasy: any scenario I could think of and more was only one search away. Tons and tons of cartoons, photographs, videos, and an active community of like-minded individuals to boot, all there! And oddly enough, what I found the most satisfying was that a lot of stuff was for sale. I was thinking that since there was a market for my fantasies, it would mean that not only I wasn't the only one, but that there were a lot more like me than I had first thought (cause you have to sell more than a few to turn a profit). All of a sudden, it was no longer just some silly fantasy, it was a business, so it made me feel very cool about it. Okay, I may be crazy after all...