Dipper soon learned that what others referred to as his omniscience was in truth anything but.

Sure, he knew lots of things. An overwhelming amount of things, sometimes. He had always wanted to know the secrets of the universe, and now so many of them were just laid out before him, ready to be conjured up with a single wayward thought.

But he didn't know everything.

He understood the general scheme of what the future held, what was most likely to occur, but when he sought out information about a specific event, he often got caught up in a whirlwind of potential outcomes, what could be drowning out what would be.

And when it came to things he was directly involved in, things got even trickier.

But some of the limits didn't have any logical reason that he could discern. Every once in a while, he would happen across something that confounded him. Books which he actually had to read to know the ending of, for instance, or people whose auras he could never quite make out.

Or the mailbox.

Dipper didn't think about the mailbox for a good number of years, too caught up in the plethora of mysteries that surrounded his life as it now was to reflect on the minor anomalies encountered in his human past. It wasn't until the triplets had dug up those old home videos made shortly before the Transcendence that he remembered the mailbox even existed.

After a long, awkward discussion with the triplets, as Mabel and Dipper retreated into another room for privacy, his sister brought it up before he could.

"So, Dipdops, what was the deal with that mailbox anyway?"

"I don't know," he reflexively answered.

Mabel stuck her tongue out at him.

He thought about it, probing the far reaches of his mind for an answer, expecting to be flooded with information that drowned out the here and now. Instead he found... nothing. He could recall the moments in which he interacted with the mailbox in excruciating detail- feel the humid summer air press against his sweaty arms, hear the birds gently singing miles away- but when it came to the specific fact that he sought, all that awaited him was a void. The origins and the creator of the mailbox remained a mystery, with him no closer to understanding it than his naive, young, human self had been.

"I d͏o̷n't ͘k̨now̨." He repeated the phrase with a voice that was stronger and colder than before.

Mabel didn't press the issue.

He was reminded of the mailbox when he next saw Soos and Melody together. She was so unlike the image of the dream woman that the mailbox had spit out at Soos' request... and yet, who else could ever have been with him? They were perfect for one another in so many ways. But did Soos still have that sketch from decades back? Did he ever want a woman who more closely resembled that portrait?

Or was the mailbox- the one that his twelve-year-old self had assumed to be all-knowing based on what, in hindsight, was rather flimsy evidence- wrong about Soos' desires, Soos' future?

He thought of it again in 3012, which was indeed... messy, but not what he'd call the end of the world given what he now had dealt with, not by a long shot. The true ending of this world, he could sense deep inside him, was still far in the future.

The demon now knew so much more than that silly little mailbox that had once so astounded him ever had, based on the obvious errors in its responses. And yet its secrets still eluded his grasp. He may have surpassed it in terms of sheer knowledge, but Dipper's youthful investigation of its origin still remained incomplete, a problem with no resolution in sight.

As the centuries went by, long after the vast majority of the infodumps which had incapacitated him in his youth, bits and pieces of the seemingly inexplicable gaps in his knowledge began to slot into place, his understanding of the world growing clearer and clearer with every insight. And soon enough, the demon was left alone with his thoughts in the mindscape, losing touch with the mortal world that he could no longer contact, with little left to do besides engaging in introspection. The secrets of the multiverse opened themselves up to him, save for that of his own future, his own potential demise.

Everything made sense now.

Except, of all things, that ancient, half-forgotten mailbox.

There had to be a reason for it. Was the universe just mocking him, leaving it so that this one minor mystery would remain for him, tearing away at him with every moment it remained unresolved, never coming any closer than he had back before his mortality was stripped from him? Or was there another involved, a higher power- higher even than him? What omniscient, or faux-omniscient, being had the ability to conceal something from the great Alcor the Dreambender without leaving so much as a trace of their involvement?

And then he realized.

Alcor laughed, a deep, harsh laugh that shook the stars.

And, with a snap of the fingers, he created the mailbox.

The flurry of letters went by fast, too fast. Alcor made sure to keep every detail the same as he remembered from being on the other side of the exchange, knowing that even a line out of place or a single incorrect word could have devastating effects for the timeline- even though parts of him wanted to change things nonetheless, wished to take advantage of the opportunity to warn his younger self of what was to come, desired the chaos and devastation that would undoubtedly result from such a paradox, longed for his existence to be erased as the future was rewritten.

At the end of it all, after sending off a final note referencing emotions that Alcor was no longer sure he could even recognize, let alone feel, the demon was left with a short stack of letters and a single video tape.

For some length of time- months, minutes, millennia, they no longer mattered to him- he perused these artifacts from a time long past, soaking in every detail of what they represented. He watched the video of Mabel sticking gummy worms up her nose countless times, his twin star appearing no longer as a romanticized abstraction but once again a creature of flesh and blood.

How many years had it been since he had last seen that face?

He knew the answer, of course, down to minute fractions of a second.

He wished he didn't.