DISCLAIMER: JK Rowling is the gem responsible for Harry Potter and his world. I only remixed her work (with a dash of some other people's) a few times.

Transmundane

Lysander felt something weird. He hadn't felt something this weird since Remus went back to the universe he'd traveled to. It was different though, like ripples in the fabric of reality. Whatever it was, it felt big.

He needed to start theorizing about it.

But to do that, he needed more data. First he did a quick probe of the Well to see if its population had changed (it hadn't). He hadn't really expected that sort of change, but it was good to check before doing something a bit more thorough. For that, he decided to use the spell that he'd once used on George Weasley to keep him invisible from the universe, something Lysander had started to think of as the "Cognition Spell" the more he learned about it. The Cognition Spell had been discovered in the far-flung future right around the time the Department of Mysteries discovered the long-range Time Travel Spell (or rediscovered, as some Unspeakables believed—there were a lot of unrecoverable records in the Time Division after a series of incidents involving freshly liberated house elves armed with chainsaws in the 2020s and Lysander had been sent to the Well before he could get around to reading the undamaged versions). Both Cognition and Time Travel spells actually tapped into reality in very similar ways. While the Time Travel Spell was powerful enough to break off a piece of reality and reshape it, the Cognition Spell was able to alter the internal knowledge of a reality. The people from the timeline that had created the two spells just considered them complements to each other—and when it took them centuries to recover from the temporal damage of the most cursory of experiments with them, they created the Memory Book and didn't dare go outside known parameters again.

After arriving in the Well of Lost Plots, Lysander was able to talk with those who also came from failed timelines, some of whom tried to experiment with the Cognition Spell (only to make the universe backlash through deportation). Once in the Well, though, there was no more punishment for dabbling with unruly spells. Using the Cognition Spell from inside the Well didn't actually work the same way, since there was no reality to manipulate, but it did have its uses as a diagnostic tool, which was what Lysander needed right now.

Lysander pointed his wand at his own head and opened his mind to outside realities. This provided him with a sensory overload and sensory deprivation simultaneously—all the realities, but no sense that Lysander himself ever existed. Well, the whole 'being fictional' thing meant he really didn't exist, but that was besides the point. He channeled his focus on whatever weird feeling it was that had prompted him to do this and found himself looking at another iteration of the Cognition Spell. Something about it made him all but certain that what he was looking at was occurring within Remus' most recent reality. Which shouldn't have been possible, since Remus wasn't there to cast the spell and he hadn't taught it to anyone, as far as Lysander was aware. But what was weirder was that the caster had sat idling for several minutes of real time before accessing a function that no one had ever identified except as what the universe sometimes did when sending someone to the Well: reintegration.

It was beyond rare—Lysander himself and a handful of others were some of the only people who'd experienced the phenomenon (not even Remus had been reintegrated, possibly thanks to something that Blair or the interloper did when he first showed up, but more likely that Remus didn't have a Generic to reintegrate with in the first place). How was reintegration even supposed to work outside of the Well, anyway? Was the Generic pulled into reality or did some other version from another timeline get pulled into his past or future self's mind? Regardless, the universe ought to notice immediately and send the offender straight to the Well—which it hadn't. But the only way that could have happened was if the mind of the person being reintegrated was already invisible. And the odds of that were...?

Yep, the interloper definitely had something to do with this. Even if she wasn't actively helping Remus anymore, she just had to be involved. Somehow.

Lysander explained to Remus what had happened elsewhere. Or rather, as much as he could figure out about what happened elsewhere, since there wasn't much to know.

"I don't like us not knowing," Lysander said. "It could be an indication that you're not the center of the universe anymore."

Remus wanted to protest that he'd never been the center of the universe, but he knew that that wasn't really true, not after meeting both the Editor and the interloper and realizing how much direct interference both had done on his behalf. Remus couldn't decide if it would be a good thing that the interloper had brought him back only to focus on somebody else. On the one hand, if his existence stopped being supported again, he probably wouldn't be warned ahead of time; Lysander and Mr. Author seemed to have done better for not having any advanced notice about it. On the other hand, his interaction with the interloper might have made it so that he'd always have that horrible of an experience of it. And now, if she focused on someone else, she'd be less likely to look out for Remus' well being—and while she wasn't particularly good at that, Remus would undoubtedly have been unable to make a difference in the first place without it.

On that note, he considered what would happen if he ever managed to get back to the universe he had once time-traveled to. He might be inserted right back into the moment that Voldemort had read his mind. And even if he appeared later in the timeline, he'd still be in the middle of Voldemort's lair. He'd have to make some contingency plans for when he got there, on top of figuring out how to get back in the first place. And that was assuming he could.

"Remus? Hello? Are you having an inner monologue without me?"

Remus was brought back to the man in front of him. "Sorry, Lysander."

"Thinking is good," Lysander said, "but it's the only real thing we've got here in the Well, so it's better to externalize it when we can."

"It's nothing, just some 'what ifs' should this lead to me getting back to reality," Remus said. "And no actual answers. You're sure that the reintegration thing happened in my latest timeline?"

Lysander shrugged. "I mean, it would make far more sense if it happened in George's time frame or in one of my time-traveling predecessors', but my gut is essentially screaming at me that it isn't. I've long since learned that ignoring screaming guts isn't a good idea—both figurative and literal screaming guts alike."

Remus hoped that the literal screaming guts didn't have a story attached to it and just tried to puzzle out the circumstances that had led to the mystery reintegration. "I guess Dumbledore might have reverse-engineered the spell I used to protect his mind, but who would he even cast it on?"

"Whoever it was," Lysander said, "they had to have had mental protection in at least one of the components being reintegrated."

Remus tallied up every person he knew to have had the Invisibility Function activated. Besides himself and Lysander (who were obviously not reintegrated, having not left the Well) and Dumbledore (who was acting in the role of caster) he could only think of one other person.

"Could it have been George?" Remus suggested. "I mean, my timeline would have had to progress thirteen years, minimum, but that's not impossible when there's already been a five-year jump from my perspective."

"But why would Dumbledore be interested in casting the Cognition Spell on George Weasley in the first place, and after over a decade, no less?" Lysander asked. "Honestly, I think he most likely started fiddling with his own mental protections just to see if he could."

"Is that one of your 'gut is screaming at you' ideas?" Remus inquired.

Lysander shook his head. "My guts aren't particularly talkative."

"Of course they aren't," Remus mumbled. "I wish I could just ask Dumbledore, that'd clear up so much." He turned over that thought in his mind. "Wait. Maybe I can ask him. Mr. Author, you around?"

"Of course," a disembodied voice said. "What else am I going to do?"

"Remember how you sent me a message through your book?" Remus asked. "How exactly did that work?"

"I just brought the book into existence here in the Well, then I wrote in it," Mr. Author explained. "The interloper did all the hard bits—I'm not exactly sure what—but I'm guessing she pulled the book from somewhere in your original timeline and stuck it in your pocket once you were in 1965."

"That means that there's two versions of the book, right?" Lysander asked. "Real and imaginary. And the unauthorized 1965 edition too, I guess, so that'd be three unless I was to summon a copy of Remus' transcription here and then there'd be four."

"I left the copy of the book that the interloper left messages in at my house in my last timeline," Remus said. "Do you think if I write in the imaginary version we have here it will update the real version that's still there?"

"It could work," Mr. Author said. "But I'm not sure if you are actually authorized to be sending messages. The interloper may have just opened up communication for me. Or she might have only copied it over the one time and I might not be authorized at all."

"Or everybody in the Well can communicate through books now," Lysander suggested.

"I highly doubt it," Mr. Author said in a dismissive tone. "Regardless, I don't think she's talking to anybody right now—and even if she was, she'd just as likely hinder as help us, so I'm not exactly going to ask for permission or clarification on what we can and can't do anytime soon."

"But sticking as close as possible to how it originally happened is our still best bet," Remus concluded. "Alright then, can you dictate a message for me?"

"To Dumbledore?"

"Well, not Dumbledore directly," Remus said. "I'm guessing Mum or Dad would have picked up the book after I disappeared. Though it's also possible one of the attacking werewolves found it after they changed back... I suppose I just need someone to write back at all first, then we can worry about getting the book into Dumbledore's hands."