Disclaimer – I do not own Gravity Falls.
A dark room had suddenly flickered to life with a small ceiling lamp, hovering over a wooden table with a chair at both ends. On one side of the table is a strongly built bearded man, wearing a black leather winter jacket and a white polo shirt underneath. On the other side, a small and frail young boy, with a small blue and white tie and a black button top. The young boy tossed a file labelled 'Top Secret' across the table towards the bearded man and started the conversation. "What, or rather who, is this thing? Does he have a name?"
The bearded man gave a quick perusal and responded to his question. "Yes, it does have a name. It's Bill Cipher"
"He was an overly-sophisticated, power-thirsty triangular dream demon with an unbelievably intricate god complex who had spent the past three millennia trying to find a new home for himself after the dimension he originated from was supposedly destroyed by him, although these reports remained unconfirmed for now. He had since taken refuge in the Nightmare Realm, the in-between space of the Multiverse. Due to its nature of not following the natural law, it is fated to self-destruct, so Cipher went looking for a more stable universe to take over. Over the last few centuries, he'd been attempting to overthrow a universe known as 46'\, the birthplace of Stanford Filbrick Pines, who I'm sure you've been told about already."
"Indeed, I have sir."
The bearded man took in a deep breath before continuing. "About a year ago, Bill successfully opened the breach between the two universes wide enough to let his so-called 'Henchmaniacs' run rampant in a small town in rural Oregon known as 'Gravity Falls'. He quickly gained a physical form and destroyed the Time Baby of that universe, granting him full access to controlling Space, Matter and Time. As we began mobilising our forces to attack Bill directly, he was defeated by Stanford's brother Stanley, who tricked him into thinking he was Ford and erased him from existence using a Handmade Memory Erasing Device developed by someone known as Fiddleford H. McGucket."
"And what happened after that?"
"Well, it's rather obvious what happened after that. Everything returned to normal."
A moment of silence passed before the young boy spoke once more. "I have a question."
"Go on."
"You said that Bill had created a physical form and took over the town, but why the town? Why not the entire universe?"
"The reason he didn't do this was because the town was surrounded by a mystical barrier set up by a previous pawn of Cipher. His name was Modoc the Wise, and he made a deal with Bill a few thousand years ago, which asked him to build a portal to link the two dimensions. The technology at the time was very primitive, and so the portal was constructed of sticks. As you probably have guessed, it did not work. Before Bill could punish Modoc for not sticking to the deal, no pun intended, he learned of the prophecy and set up the barrier to prevent Bill from taking over the rest of the world, should he have succeeded in his plan. He then lit himself on fire to escape from Bill's clutches."
"Well, I guess we're lucky that he was defeated before he could collapse the barrier."
"Not exactly."
"What do you mean, sir?"
"Bill was defeated because Stanley tricked him into thinking he was his brother. They made a deal that Bill could enter his mind to get the equation to collapse the barrier and spread his Weirdmageddon to the rest of the universe. His physical form turned into stone and his mental form was destroyed inside of Stanley's mind when it was erased by Ford. That should have been it. But recently there have been energy surges coming from the statue that seem to be giving us a hint of his possible return."
The young boy stammered for a second before responding. "But he can't return, his mental form contained his personality, his thoughts, his desires, everything that made Bill, Bill. His physical form was just merely a protective shell to prevent damage. With his mental form destroyed, his physical form would become a shadow of his former self. It would become nothing more than a statue. So how is it that he's somehow still alive?"
"He's still alive because the only true way of defeating him was through the Zodiac, but Stan and Ford couldn't help arguing because Ford was being self-centred. When Bill travels to the mindscape in his physical form, he doesn't need his powers, so he leaves his powers within the confines of his body, because in the Mindscape you only need to think about what you want to happen, so Bill could just think about using his powers and that would be it."
"And his powers are growing?"
"Yes. At the moment, his powers are trapped within the statue, but all it takes is a single shake of the hand, and his powers will be transferred to someone else."
"And Bill rises once again in the body of a human."
"Exactly. It will take some time before the powers begin affecting the mind of the host, but once they go mad with power, Bill will be reborn."
"So, what do we do?"
The bearded man paused for a moment, then gave his answer: "I don't know."