Hermione accidently loans Harry her fantasy diary, instead of her history notebook. In it, he finds a variety of sexual fantasies involving himself. Most of them are Dom-Harry and sub-hermione, and some involve harems.
Some examples:
How many fantasies does Harry read, and what does he do, afterward?
Some examples:
In a world where Tom Riddle went for political power, rather than terrorism, Harry goes to a slave auction, observes several nude muggleborn girls, and buys Hermione.? He takes her home on his broomstick, and they join the Mile High Club on the way there.? More sex happens when they get to Harry's place, along with quite a bit of domination.? (She may have written a few sequels to this one.)
Hermione is playing strip poker with Harry, Ginny, Luna, and 'Nymph', and Harry turns out to have the best poker-face, or maybe just the best luck.? After all the girls are naked, Nymph reminds them of a rule that the losers must buy back their clothes, and not with money.
Oddly, Hermione is the Keeper of the Holyhead Harpies, while Ginny is the Seeker, the Patil twins are the Beaters, and Katie, Alicia, and Angelina are the Chasers.? Harry is the owner of the team, and a clause in their contracts requires the team members to be sexually available to the owner.
Harry and Hermione have a quiet wedding in a little village church, with just their close friends and family in attendence.? Then they get a room at a cozy bed-and-breakfast, and make slow, sweet love all night long.
Harry joins Hermione's family for summer holidays, and because their both old enough to make their own descisions, they get a room to themselves at the resort.? (Might involve Fleur, or just some random French maid.)