Stanford Pines has a file containing information on Bill Cipher and various sighting of him throughout history. The file contains pictures and a page ripped out of a book, with images of a pyramid (presumably in Egypt) and the Eye of Providence. Another page in the file is titled "Alligans Contractus" (which is latin for "Binding Contract" with a picture of an old man shaking Bill's hand, both of which are surrounded by a blue flame, signifying the man is making a deal. There is also a trifold paper with three titled: Our World (with a drawing of a human head), Mindscape (with a drawing of a person and Bill and the coded message: Black and White), and Nightmare Realm (with a picture of Bill).
The page ripped out of a book ("book excerpt" on images to the right) reads: "Pyramids, also known as square-cones, are found all around the globe and have deeply mysterious origins. Modern engineers marvel at their seemingly impossible construction, but many don't realize they're actually just the skeleton remnants of an ancient race of large triangular dinosaurs who had very blocky bones. The Cycloptostoneosaurus was a feared predator and roamed the plains of North Africa where it subsisted on a diet of warthogs and meerkat, is made tender by their carefree lives and trouble-free philosophies. The reign of the pyramid continued well into the 18th century where a young George Washington once saw one on summer vacation and swore that he would found a nation with the sole purpose of putting an image of it on the back of dollar bills. Pyramids today are mainly tourist attractions and setting for conspiracy movies. Like that one where the guy has to steal the declaration of independence. You know the one, "Conspiracy Hank Goes Overboard". If you ever get a skateboard go to Egypt and try riding down the side of a pyramid. I hear that's really encouraged."
Bill Cipher is not you average demon, he can take form of anything he wants. Because his body is stone, he doesn't have his full power. He can turn into his normal form, but he could only hold it for at least a minute, before it starts to feel like his body is burning in lava. He bound himself to a human, and he has been apart of this human for so long that the being that used to be wasn't anymore. It was now just Bill, and he was able to do with it as he saw fit. The body adapted to him and now he was able to use a bit of his ability.
Bill seemingly was defeated by the Pines, but as he was supposedly shot with the memory swipe gun, he had said it wasn't the last of him. In which he wasn't lying. Bill doesn't have all of his memories, some of them were wiped out completely leaving him to see things from time to time and swearing up and down that he has seen it before, though he cant remember.
Formerly existent only in the mindscape before succeeding in gaining access to the real world.
For one trillion years I've been trapped in my own decaying dimension, waiting for a new universe to call my own. Name's Bill! But you can call me your new lord and master for all of eternity!
Sometimes
dreams
can
be
really
really
scary
The prophecy of the zodiac hung heaviest of all over Bill's mind. This prophecy explained that if ten particular individuals gathered in the circle designed by the ancients who had known Bill, they would be able to stop him; however, this would not come to pass if any of them broke the chain.
Despite this, Bill's own ego proved to be his most fatal flaw, as it led him to underestimate the "mortals": he failed to recognize Stan's trick, driven by the possibility of learning how to bypass the bubble over Gravity Falls, and did not realize he was at his most fragile while in the mindscape. His elimination also revealed that, while in the mindscape, he was as vulnerable to erasure via the memory gun as all other thoughts.
In order to prevent Bill's chaos inside someone's mind, one must light nine candles and place their hand on the victim's forehead. Say the following incantation: Fidentus omnium. Magister mentium. Magnesium ad hominem. Magnum opus. Habeas corpus. Inceptus Nolanus overratus. Magister mentium. Magister mentium. Magister mentium. If spoken the reciter of the incantation's eyes will turn blue and will be brought to the victim's mind on how they picture, where they have to find a way to stop Bill themselves.
There are also three known preemptive methods to stop Bill from entering minds. The first known method is a shielding spell that involves moonstones, mercury, and unicorn hair. The second method is placing a physical barrier around the mind, such as Ford's metal plate, though Ford stated it's not the safest method. The last method is "encrypting" a subjects thoughts, making it too difficult for Bill to read. It is safer than the second method and more mobile than the first, but very time consuming.
Reality
is
an
illusion
buy
gold
bye