This has even less effort in it than the other chapters, and all of this was meant to be crack, so pardon any mistakes.
And no, I am not planning a full story any time soon. I have too many WIPs as it is and I'm going to be heading to grad school soon-ish. My plate is full.

Option 1: Hermione tells the truth

Lord Elrond raised his head from his hands after what Hermione could only classify as thirty solid minutes of silent, internal screaming. The boys were dead asleep in a pale-faced Glorfindel's arms, their soft snores the only sound in the heavy silence.

"Allow me to recap," Elrond said in a deceptively calm voice. "You—all three of you—were once legally recognized adult mortals blessed with magic. Your Harry united three artefacts and lost the ability to pass into the mortal afterlife, at which point Eru Iluvatar himself brought you here as an act of mercy. All of this you learned through the Valar themselves—"those idiot gods" as you put it—in a dream."

"Correct," Hermione agreed primly.

"And you expect us to see you as adults?"

"Ah—well, yes."

"You do realize that we eldar reach our majority at one hundred years, correct?"

"We're...special cases?"

A beat of silence, then "no, no that won't work. Forgive me, but you are still children by any metric we might use."

Hermione made a frustrated sound. "But I literally just became an adult!"

"That is unfortunate," Elrond agreed in a dry voice. Hermione realized her objection had sounded very much like whining befitting an actual child and shut her mouth with a grimace.

"Perhaps a compromise?" she suggested. "You consult us rather than making unilateral decisions about our upbringing and we'll do our best to listen to you in return."

After a moment's thought, the elf lord nodded.

Option 2: Hermione lies through her teeth

"She was lying," Glorfindel said when he and Lord Elrond retreated to the study.

"Oh, most assuredly," Elrond agreed tiredly, plopping down into his chair with an appalling lack of elven grace. "But I think her unintentional points of honesty have given me enough clues to piece together an approximation of the truth."

Glorfindel raised his eyebrows. "Which is?"

Elrond sighed and slumped back in his chair, head tilted toward the ceiling. It ways days like this that he sorely missed his twin. Elros would have charmed the truth right out of Hermione and gone off to play with the children without them noticing they'd told him anything at all.

"In short, I believe they were born here, Ron and Harry at the same time and perhaps together during the War of Wrath. Hermione must have been Celebrimbor's daughter, not sister, likely born shortly before he was killed. All three children were hunted by the Enemy and killed." His voice dropped to a low, haunted timbre. "Brutally killed. They must have struck up a friendship in the Halls of Mandos, though why they were sent back here I cannot begin to fathom."

A beat of silence passed.

"Well, shit," said Glorfindel.

Bonus: Ginny, Luna, Neville

Ginny woke up naked, which was very Not Good. She also woke up tiny, which was equally Not Good, and in the middle of a silver-gray forest. "Harry," she sighed, aggravated, as she examined her tiny fingers. "Honey, what did you do this time."

Belatedly, she realized there were two other tiny figures laying near her. "Oh good, Luna!" she said, reaching over and shaking her best friend awake. "And... Neville?"

Neville startled awake as Luna yawned and smoothly sat up. "Oh Merlin," he gasped, examining his hands. His eyes moved lower. "OH MERLIN."

"The Nargles are at it again," Luna sighed, combing her hair away from her face. "Next thing you know, there'll be Wrackspurts everywhere!"

"Right, Lune," Ginny agreed absently, busy searching for her wand. Much to her frustration, it seemed to have vanished along with her clothes.

"Hold on, what's that?" Neville murmured, squinting and shading his eyes with one hand as he stared into the distance. A humanoid shape resolved itself from the vague mists. "A person, I think," he said to the girls. "Coming toward us at a good clip, too."

Ginny, normally decisive and quick to act, was stymied. "Well… should we… run?" she said aloud, testing her words. Immediately, she frowned. They were naked and tiny, stripped of their wands, and in completely unfamiliar territory. "And none of us can apparate, especially without a wand...bugger!"

"Uh…" Neville said nervously, interrupting Ginny's muttering, "Its a person, but… he's moving really fast, Ginny."

The redhead moved closer to him, squinting and shading her own eyes to see what he was talking about. She spared a second to note that her eyesight had sharpened quite a bit. "Merlin, fine, let's at least hide," she decided.

They stumbled over to a nearby tree trunk, putting the huge thing between themselves and the newcomer. Ginny crouched tensely, reviewing every piece of wandless magic she knew she could perform. It was a pitifully small list, but at least it was something. Neville appeared to be doing the same thing. Luna was completely unbothered as she stared at the trunk of the tree, her palms pressed against the rough bark, and Ginny had the strangest feeling that she was trying to communicate with it.

Before she was quite ready for it, she could feel the heavy-soft footfalls in the ground. She tensed, breath catching in her throat, muscles coiled like springs. A man ran past, his head on an alert swivel. He did a double take upon spying them, screeching to a stop and doubling back.

"Stay away!" Ginny barked (or rather, yipped), hands raised in preparation. A little corner of her mind noted that the man was absurdly beautiful and dressed in some of the strangest armor she had ever seen. There was a bow (?) strapped to his back, and knives at his sides. His hair was long and platinum blond and stupidly shiny, which made her think Malfoy and did absolutely nothing in the man's favor.

"Children, babies, what are—?" he muttered to himself, trailing off with a shake of his head. He crouched a good distance away, holding his hands out to show that they were empty. "You share my tongue, dear one?" he asked, addressing Ginny in an infuriatingly condescending tone.

It took her a moment to decipher the strange phrasing, but she managed it. "Yeah, so what?" she challenged, tossing her head. "Go away!"

He chuckled a little, disbelieving. "Ah, I am sorry, child, but I cannot leave you out here on your own. You might be injured, or become lost."

Ginny bristled, but Luna cut her off. "We should go with him," she said, pressing her tiny hand to Ginny's shoulder. "The trees say he's going to help us find people."

"Better than wandering a forest naked," Neville agreed sotto voce.

Ginny considered this, lips pressed in a tight line. After a moment, she yielded, heaving a sigh. "Fine," she said, looking to the man. "But I've got my eye on you."

The man, whose name was Rumil, turned out to not be a man, but rather an elf. Coincidentally, all three of the former wizards had become baby elves. Ginny and Neville took it pretty well, all things considered; Luna nodded sagely, as if this was exactly as she predicted (which, to be fair, she might have).

Rumil wrapped poor Neville in his cloak, then stripped off his tunic and undershirt and draped those over Ginny and Luna. After a lengthy ten-minute argument, Ginny grudgingly agreed to sit on his shoulders while he carried Neville and Luna. They found his gait, even when running, to be unnervingly smooth, almost like the gentle rocking of a muggle car. After a few minutes it went from 'weird' to 'weirdly soothing.'

I'll just rest my eyes a second, thought Ginny, cheek smooshed against the top of Rumil's head.

This is how Rumil arrived back in Caras Galadhon burdened with three snoozing elflings, a dazed, disbelieving expression on his face. His younger brother was the first to spot him. He descended quickly from the lookout post, a strange expression on his face.

"Rumil," he said, eyeing the children. "What strange tidings do you bring today?" which is the Lothlorien equivalent of "what the actual hell did you find this time?"

"Children, Haldir," he replied, shifting Neville a bit. "Elven children."

The marchwarden froze. His eyes flicked to Luna, then Ginny, then finally Neville. "Impossible," he whispered, reaching out to brush Neville's hair away from his unmistakably pointed ears. "There have been no births. How can this be?"

Rumil shook his head. "I know as much as you, brother. The children were… not forthcoming. Someone hurt them, or I am mistaken. But that is unimportant right now. Our Lady must be told."

Haldir visibly gathered himself. "Of course. Of course. I will inform her myself." He straightened, squaring his shoulders. "Take the little ones to the healers and have them seen to."

"Of course," Rumil said, bowing slightly in acknowledgment. The brothers parted ways, completely oblivious to the pandemonium that was about to erupt across all the elven settlements, starting with their kin in Imladris.

But that, my friends, is a story for another time.