Draco Malfoy, 17 year old pureblood wizard, was sent to Azkaban after the war. However on his 18th birthday he comes into his magical inheritance. He is a natural submissive with the ability to produce children, specifically creature children, without the use of a potion.
While this inheritance is rare and cherished, Draco is still a prisoner in the eyes of the ministry, so they decide to sell the Malfoy heir off to his dominus creature wizard. One Harry Potter hears of the news. He had already realized that Draco was his mate, he just needed an excuse to get him out and now he has one.
Buying the young submissive blonde is a done deal for the golden boy and so Draco becomes a Slave Of Sensation.