Disclaimer: Usual disclaimers apply. The proper people have the proper rights over the proper things, and I do not, which is also proper.
Pair the Spare
Forty-year-old Luna Scamander stood in her nightgown looking through her closet for something to wear. She was on her own that weekend – the twins were in their third year of Hogwarts, and her husband Rolf was at a conference in the Ivory Coast – so technically she didn't need to put anything else on. Luna was not the type to laze around the house all day in her bathrobe, though – if there was lazing to do, she was going to do it in proper clothes. Preferable something in a cheerful colour.
She rifled through her closet, looking for something that reflected her mood that day. The periwinkle robes weren't it, neither were her nearly fluorescent yellow ones, the safari outfit was right out, but then something shiny caught her eye near the back. She hadn't thought about the her old spangled-silver dress robes in a few years, but seeing them again, the memories came flooding back.
When her friend Harry Potter had asked her to be his date to Professor Slughorn's party, she had been overjoyed. No one had ever asked her on a date before, and that it was the boy she had a crush on, however unrealistic she thought that crush was, was just icing on the cake. She hadn't even minded that Harry specified that he was just asking her as a friend – it felt wonderful to be asked in the first place. The evening was wonderful, even with Harry's disappearance for a disappointingly long time in the middle of it, and she looked back upon it as the highlight of her fifth year at Hogwarts.
She knew Harry liked her best friend Ginny Weasley, and that he wouldn't have asked her if Ginny had been available, but Harry had his pick of the girls at Hogwarts that year. She later found out that Ron Weasley had shouted to Harry "you could have asked anyone!" when he heard Harry had asked Luna, and as hurtful as those words were when relayed to Luna, they were true. Harry was the toast of the wizarding world that year. He could have chose anyone. But he chose Luna.
It was a novel experience for her at the time, to be chosen. All her life she tended to be an afterthought to people. As a child, she became friends with Ginny Weasley because they were the only two daughters of magical families in Ottery St. Catchpole. In school, when partners were assigned by teachers, she got put with whoever was left over. "Pair the Spare" seemed to be the story of her life.
In fourth year in Dumbledore's Army, during spell practice, she was paired with whichever person was slowest to partner up. In sixth year, when she, Ginny and Neville Longbottom were running the D.A. and trying to avoid the wrath of the Carrows, Ginny often hinted that Neville and Luna should get together romantically, as Ginny intended to resume her relationship with Harry once he had defeated Voldemort. Neville was a good and caring friend, and had he shown any inclination to pursue the idea, she would have agreed to it, but Luna had recognized the reason behind Ginny's good intentions – Luna and Neville were the leftovers. The spares.
It was the same with Dean Thomas, after their rescue from Malfoy Manor, when they stayed at Shell Cottage for all those weeks. With Harry, Hermione and Ron planning their next move, and Bill and Fleur trying to enjoy what semblance of a married life in wartime as they could, Dean and Luna spent long periods of time together and grew close by default rather than any chemistry or real friendship. Other than a shared imprisonment and an interest in art, they had little in common. They didn't maintain their acquaintanceship after the war, and Luna hadn't seen or heard from Dean in twenty years. They had been thrown together not by any choice by either of them, but because they were left over.
Even after school, the pattern continued.
Luna's first time with a man began at a Muggle bar in Cardiff, where she was sitting with another young woman from the magical naturalists conference she was attending, drinking a wonderful green Muggle drink called a grasshopper. They were approached by two young Muggle men, and the one who ended up chatting with Luna was clearly acting as a wingman, to make his friend's attempt to pick up the other naturalist more successful. When Keith asked her back to his place "for a nightcap", Luna knew he simply asked her because she was there, rather than out of any real desire on his part, and had she not enjoyed those grasshoppers so much, she likely would have turned him down. Luckily, Keith was caring and tender, and made sure Luna enjoyed the experience, but there was no question of them staying in contact the morning after. They were simply there at the bar at the same time.
Even her husband Rolf. Rolf was thirteen years older than her, and other than both being on the same five-month expedition to Peru, and both being naturalists, they had little in common. But they were the only single people on the expedition, and so they were thrown together repeatedly over the months. It was grief over her father's recent death, and desire for a family of her own, that drew her to Rolf, and desire for companionship that drew him to her, more than any real spark among the two of them. If there had been another single woman on that expedition, Luna honestly doubted that they would have got together at all.
Rolf had turned out to be a kind and caring man, a surprisingly attentive husband, and a loving father. Although she hadn't been in love with him when they got together, she grew to love him over the years, and wouldn't trade him for the world now. But they fit the pattern – he didn't choose her, and she didn't choose him, so much as fall together because they were there.
When Rolf asked why she kept the spangled-silver robes, she told him that they were one of the few things that she and her father were able to salvage from the wreckage of her childhood home after the war. That was certainly true.
What she didn't tell him was that they were a reminder of the one brief, shining moment, when she was fifteen years old, when however brief and innocent it was, someone had chosen her.