A/N: I thought a long time about how/if I could actually write about someone "maliciously missing." Finally, the right prompt at the right time led to the right idea, and I hope that I've done that prompt justice. As always, JK owns the Potterverse, I just enjoy playing in her sandbox.
The day after the Battle of Hogwarts, Luna Lovegood woke from her slumber next to her good friend Neville Longbottom. Slowly easing herself off the bed, she gathered the few belongings she had left scattered about the night before, and walked out the front door of the great castle.
When Neville finally awoke a couple of hours later, he noticed that Luna was already gone. Thinking little of it, he went about preparing for the day, and met up with others who had been too exhausted to leave Hogwarts in the Great Hall. It was only after breakfast had been consumed and people started preparing for life after the end of the reign of Voldemort that Neville realized Luna was not in the Hall, and checking a few out of the way rooms, came to the conclusion that she had left the castle entirely without anyone having seen her depart. Assuming that she had gone home, Neville asked one of the Weasleys to Apparate him to their place, since he had never actually been to the Lovegood home, but knew the Weasley family lived nearby.
When he arrived at the Rookery, he saw that it was in the process of being rebuilt, likely due to the rough treatment it had received from Harry's visit a few weeks prior. Walking up to the front door, he saw a parchment had been stuck to it, but it was simply a note from Xenophilius saying that he would be off exploring Sweden while the house was under repair. Neville tested the front door, but it was still securely locked. A quick look around the perimeter showed no signs that anyone other than whoever had been rebuilding the house had been around for days, and using the little bit of magic sensing he had learned from an old book in the Room of Requirement, he determined that Luna had not been home since she had been kidnapped off the train at Christmas. Having found no answers here, Neville returned to Hogwarts for the time being to help with the repairs taking place there.
A few weeks later, Neville heard that Xeno Lovegood had returned home, and went to pay him a visit. No one had heard anything from Luna since the day of the Battle, and Neville hoped that nothing horrible had happened to his friend. However, Xeno had not heard from his daughter either, though he was quite sure that she was fine. When Neville asked him how he knew, Xeno merely remarked, "A father knows." Disappointed but undeterred, Neville left.
Weeks turned into months, which turned into years, and while life had returned to normal for most of the British witches and wizards, Neville continued to search for Luna. Having scoured the entire country, Neville moved on to the closer parts of Europe. When that came up empty, he continued throughout the continent. That search also turned up fruitless, so Neville kept exploring farther and farther east, even going so far as to pay a visit to Hermione and Ron in Australia, where they had moved after discovering Hermione's charm on her parents had broken almost immediately upon their arrival in Sydney, and a full year in Oz had made her parents rather unwilling to return to the Isles.
Ten years after the Battle, Neville was still hunting for any word about his wayward friend. He had come to the United States, and was sitting outside one of the many coffee shops he'd discovered in Seattle. How a single city could support such a thing (and why they favored intensely strong coffee over his much preferred choice of tea) baffled Neville. Suddenly, his magic sense picked up on something very familiar, which accompanied a well-dressed woman sitting down at his table.
"I wasn't expecting anyone to actually come this way, but I suppose if anyone would, it would be you, Neville," said the woman, with the merest hint of an accent.
"I'm sorry, I'm afraid I don't…" began Neville, before taking a close look at the necklace the woman wore. Rather than the pearls he had initially assumed, the baubles were instead large pieces of cork shaped into spheres. The woman removed her hat to let her blonde hair loose, and silvery grey eyes shone behind the sunglasses she wore.
"Oh, I'm quite sure you do, Neville," said Luna. "After all, only you kept looking for me this long. The others gave up rather quickly, if they even started. Why did you keep going, Neville?"
Neville had been stunned into silence by finally finding Luna. After a moment to regain some composure, rather than answering her question, he blurted out the first thing on his mind. "Why did you leave and not tell anyone?"
Luna smirked at him. "I suppose I should answer your question first, since you don't seem to be in a fit state to answer mine just yet. Why did I leave? I wanted a fresh start. Somewhere that no one has heard of 'Loony' Lovegood. Somewhere that doesn't automatically assume that being the daughter of the editor of the Quibbler makes you an insane crackpot. Somewhere that respects you for being who you are, and doesn't try to change you through bullying. Somewhere that isn't England. Do you understand, Neville?"
Neville nodded, but frowned. "I understand why you left, but why didn't you tell anyone? Not your dad, not the elves, not even me. Maybe you're not the only one who needs to start fresh."
Luna caressed his cheek. "I'm sorry, Neville, but I needed some time alone. I needed to find out if I could be something more than I had been. And now I know that I am much more than 'Loony.' So tell me, why did you come after me?"
Neville blushed slightly. "At first, I told myself that I was just looking for a very good friend. Then, I kept going because I enjoyed travelling, in addition to wanting to find my friend. But now, sitting here having finally found you, I realize that I kept going because I think I feel something more than just friendship for you, Luna. And I wouldn't have stopped until I found you, because I needed you to know."
He looked up to see Luna dabbing at her eyes with a napkin. "I'm touched, Neville. I truly am." She snuck a quick look at her watch. "I'm afraid I have to run off again to a meeting, but I don't want to leave you behind this time. Come with me?" She held out her hand, making her invitation very clear.
Neville took her hand in his with a grin. "Always."
A few months later, Xeno Lovegood received a package from Neville. Inside was the message "I found her" on the back of a wizarding photograph that showed a dark haired man and a blonde haired woman standing at an altar together. Xeno smiled, and mentally began preparing for the cover of next month's Quibbler.