I’m not sure if this counts as dark but to me it is. To be honest I sometimes have imagined that I shrink and my ex, a giant in this fantasy, kidnaps me and my boyfriend, also big, has to rescue me. I feel bad sometimes thinking about it because it does involve my ex but I can’t help it and I always think more about my boyfriend rescuing me. My relationship means the world to me so this fantasy is my dark secret.
Personally, I had always liked size related movies as a kid: like Honey I Shrunk the Kids and when I got into my teens I watched more content like: Inner Space and slowly learned that I had more than a casual curiosity while browsing DeviantArt. A lot of the mass media I had consumed was not M/f related but I soon realized that I preferred to fantasize and see M/f content over the giant woman media that typically dominates the field.