Story Timeline:
Prologue at Shell Cottage.
Begins after Battle of Hogwarts.
Finishes with different Epilogue.

Alterations to Canon:

None.

Pairings:
Harry/Luna
Harry/Multi/Harem

Prologue:
At Shell Cottage Luna is resting in one of the bedrooms when she hears groaning coming from the next room. Putting her ear to the wall she realises that the room next to the wall is the shower stall and that that's where the moaning is coming from. Being somewhat of a pervert Luna barely hesitates before casting one of her favourite charms, the 'One-Sided Transparency Charm'.

A one-way window appears in the wall and Luna is treated to the sight of Harry, his rather impressive cock in his hand vigorously masturbating. She decides his idea is a good one and brings herself off as she watches. As Harry washes his rather substantial mess off of the glass partition Luna comes to a decision.

When she was locked away in the dungeons of Malfoy Manor she had repeated feared not just for her life but for her virtue, surrounded as she was by Death Eaters notorious for their revels. Now that she's been rescued it seems only natural that she would offer her saviour as a reward the virtue he'd saved, she resolves to lose her virginity to Harry.

Story:
At Hogwarts after the Battle there is finally peace and quiet and Luna figures to herself that now is the time to follow through on her earlier plan. Watching Harry as she waits for the appropriate time to take him aside and explain her intentions to him she witnesses as a number of other girls likewise eye Harry hungrily, clearly entertaining their own ideas about the Hero.

In the aftermath Hogwarts has become the gathering point of both the survivors of the battle, their families, the remains of the Light forces as well as members of the resistance underground and people who were just on the run.

Amongst these crowds Luna watches:

- Gabrielle, who has definitely matured swiftly since her older sister's wedding, smiles very pleasantly and walks very closely to a partly amused and partly aroused Harry. She also rather blatantly flirts with Hermione and Ginny.

- Ginny, who constantly chews her bottom lip and blushes and looks away whenever she makes eye contact with Harry. Which only allows Harry to give long appreciative looks at Ginny's body.

- Katie, Angelina and Alicia who each give him a big kiss on the cheek, though Katie also takes the chance to goose Harry on the bum and give long, lingering and considering looks in his direction.

- Cho Chang, who looks rather depressed and longing looks at Harry as though reminiscing over a past regret. Luna resolves that if Cho promises not to cry again she'll invite her.

- Padma and Parvati, the later cajoling the former, that earlier before the battle Padma had said if she survived the battle she was going to lose her virginity to the bloke who fought the hardest. Padma says that she didn't mean immediately, Parvati warns she'll just chicken out... and that they both know why, it's because of who she'd have to shag, Harry himself. Parvati says she's already decided on Harry and what better way is there to thank Harry than identical twins?

- Susan Bones, who has secretly had something of a crush on Harry ever since the DA and had front row seats to the show down between Harry and Tom, is just about ready to drop to her knees and service him in the Great Hallfrom what Luna can tell.

- Lavender, who is now sporting the curse scar across her throat, shoulder and jaw beneath her left ear, who is despondently going through the motions, helping with the reconstruction and caring for the injured but smiles her first smile for Harry when he says he's glad to see she's okay.

- Daphne and Astoria Greengrass, both now uncertain about the threat hanging over them as either could turn out to be the unspecified 'Heiress Greengrass' contracted to marry 'Scion Malfoy' by the betrothal contract that Lucius extorted out of their father. Their best option is to get Harry to coerce Draco into rescinding the betrothal now that his father is in Azkaban for life.

- Pansy Parkinson, who publicly thanks Harry, rather emotionally, for ending her nightmare, but saying nothing more specific.

Deciding that if Harry deserves her virginity as a reward for saving her from the Malfoys that the other girls deserve the chance to offer Harry the same or something similar for saving them all from the Dark Lord and his forces, Luna plans to arrange for every girl interested to have just that chance.

She approaches Gabrielle first and explains her intention and asks if Gabrielle would be interested in participating and helping arrange an orgy. Checking that the Room of Requirement survived the Fiendfyre they work to design an appropriate setting, organise with elves to provide refreshments, obtain and brew some potions for medicinal and entertainment purposes and begin writing invitations.

Additional Possibilities:
Hermione has a horrible argument with Ron when he unwisely suggests that her parents, 'those muggles' will be fine where she sent them and that there was no reason to leave. A bawling Hermione crashes into the Gryffindor girl's dorms and finds Lavender, Padma and Parvati all in varying states of undress and trying on different lingerie.

The three girls decide that there's nothing to lose by offering and tell Hermione about the orgy that has been organised to reward Harry and if maybe she'd like to blow of some steam with some meaningless sex she should tag along. A mortified Hermione, reflecting on the somewhat shameful thoughts she'd had about Harry back when it was just the two of them in that tent, especially after accidentally seeing his morning wood once, decides there's no reason not to and comes with them.

Fleur learns about what is happening from Gabrielle and after consulting with Bill tells Gabby that she'll come too, if it's okay with Gabby. Gabby is surprised and Fleur explains that she and Bill have an arrangement. Occasionally they have company in bed, twice since their engagement and once since the marriage, it's always been a woman and Fleur enjoys the company of the fairer sex but Bill isn't selfish or unfair and is happy for Fleur to indulge the odd dalliance, but has no interest in blokes himself. Fleur admits slyly that she'd entertained the thought of rewarding Harry for rescuing Gabrielle and then later herself from Krum's Crucio but had decided that at just fourteen Harry had been too young back then, but things are different now.

One of the teachers: Babbling, Vector, Sinestra.
She has always had a naughty fantasy about seducing or being seduced by a student, a boy or a girl, or both at the same time, but never had the nerve. Harry's technically not a student but it's near enough to suit her and recently reminded of how short life can be decides to throw herself into the mix.

Perhaps Narcissa wants to thank Harry personally?

If you want to alter canon maybe Tonks survived the battle but had parted company with Remus after he buggered off on her after the birth of their son and decides that an orgy sounds like her cup of tea.

Megan Jones, Lisa Turpin, Tracy Davis, Fay Dunbar?

Epilogue:
Several of the girls end up becoming Harry's wives and consorts, Luna definitely included in their number, but several times a year they host a 'reunion' where any witch who participated in the first orgy and happens to be single (or like Fleur have an open-minded significant other) are free to return for an evening of fun, sometimes an orgy, sometimes a party, sometimes an adventure.

There's a running joke that if any of the women turn dark or evil then they'll be uninvited from the reunions and so Harry and his wives are still protecting Britain from any new dark movements.

A debate is held, perhaps mid-orgy, about how, with fewer witches returning as more settle down or move away, that maybe the original participants only rule might be replaced with a sponsorship or voting system as several of the women have friends they want to bring.