The Love of Dragon

I was pushed off the city wall by my stepsister, and a giant dragon caught me. It said I would give birth to a warrior who would overturn the world in the prophecy, and the price was that the child would belong to it. I agreed, but this thousand-year-old dragon began to bring me roasted cattle every day, pave my nest with gems, and carefully rest its claws on my belly when I was pregnant. We had a deal, so why did it fall for me first?