Somehow I knew I was dreaming, which chilled me to my bones.  I had never been fully conscious during a dream, not since 1982, when Bill shared my mind. 

I found myself in a colorless field of wheat that swayed to a wind I could not feel.  Everything seemed fine, but I knew it was only the calm before the storm.  Suddenly, a harsh wind blew around me, flattening the grain around me into a triangular shape.  I maniacal laughter broke the silence, a sound I hadn't heard in three decades.

"I know that laugh... Bill! Show yourself!"

The all seeing eye materialized in front of me. "Well, well, well, well, well, well, well, well, well, well, well!" He copied himself with every word, forming a ring around me. "Aren't you a sight for sore eye! Stanford Filbrick Pines, my old pal!"

I grit my teeth. I could never seem to get rid of this guy. "Bill Cipher. What do you want from me?"

He rolled his singular eye. "Oh, quit playing dumb, IQ!  You knew I'd be back!  You think shutting down that portal could stop what I have planned?"  All the Bills merged into one, glaring at me. "I've been making deals, chatting with old friends, preparing for the big day! You can't keep that rift safe forever."  He snapped his fingers, creating a copy of the rift in my dream.  "You'll slip up, and when you do..." 

He smashed the rift onto the ground, creating a massive portal in the shape of an upside-down triangle, making the wheat field field around me set ablaze. 

"Get out of here! You have no dominion in our world!"

Bill seemed amused by my anger.  "Maybe not right now, but things change, Stanford Pines!  Things... change."

Several images flashed in my mind as I woke up with a start. "He's coming," I whispered. "I have to warn them." I ran down the hall, shouting, "family meeting!"

Y/N was first to arrive, followed by the twins. I sighed. I guess Stanley still wasn't talking to me. "Ah, children. Come in, come in!" I swept all the pieces of parchment aside.

Mabel's eyes widened. "Ooh, mysterious scrolls and potions! Are you going to tell us we're finally of age to go to wizard school? Is there an owl in this bag?" She started rummaging through my bag.

I hastily snatched it back. "No! I can assure you if there's an owl in this bag, he's long dead." Y/N frowned at me. "Now, do any of you recognize this symbol?"

All three of them gasped. "Bill," Dipper said gravely.

I blinked, surprised. "You... you know him?!"

"Know him? He's been terrorizing us all summer! I have so many questions and theories..." He clicked his pen anxiously.

"Dipper's been pretty paranoid after Bill turned him into a living sock puppet," Mabel summarized.

"The important thing is, we defeated him twice."

"Once with kittens and once with tickles!" Mabel smiled innocently.

"It was a lot more heroic than it sounds."

I shook my head. "The fact that you've dealt with Bill is gravely serious."

Dipper narrowed his eyes. "So, how do you know Bill?"

"I've encountered many dark beings in my time, Dipper. What matters in his powers are growing stronger, and if he pulls off his plans, no one in this family will be safe."

Y/N gave me a suspicious sideways glance, noticing that I hadn't answered the tween's question.

"Fortunately, there should be a way to shield us from his mental tricks. A way to Bill-proof the Shack. All I have to do is place moonstones here, here, and here, sprinkle some mercury, let's see... I always forget the last ingredient!" I flipped through journal one, trying to find the right page. "Ugh, unicorn hair."

"That's not like, rare, is it?"

"It's hopeless. Unicorns reside deep within an enchanted glade, and their hairs can only be obtained by a pure good-hearted person who goes on a magical quest to find them."

Mabel let out an excited whoop. "Grunkle Ford, can I please go on this quest? I am literally obsessed with unicorns! My first word was "unicorn," I once made my own unicorn by taping a traffic cone to a horse's head. Are you even looking at the sweater I'm wearing right now?! Not to mention that I'm probably the most pure of heart person in this room. Except maybe Grauntie Y/N."

Grauntie?! I see Mabel found out about the engagement, then. I covered my mouth to stop from laughing. Y/N glared daggers at me. "You can go on this one alone, Mabel. One encounter with unicorns was enough for me." She shuddered at the memory.

"It won't be easy. Take this." I handed her my trusty crossbow. "I haven't been in this dimension for a while. It's okay to give children weapons, right?"

Y/N shrugged. "That sounds right to me."

"Candy, Grenda, Wendy! Clear the afternoon!" She raced out of the room.

"So, what are the odds she gets that hair?" Dipper asked.

I sighed. "Unlikely. I've dealt with unicorns before, and if I had to describe them in one word it would be... frustrating."

Y/N grunted. "Agreed."

"So, what're we gonna do about Bill?"

I winced at his improper grammar. "Follow me." I led him behind the vending machine and into the elevator, going down to the second level. "Welcome to my private study, a place where I keep my most secret knowledge. Even your uncle Stan doesn't know about this place. If we can't Bill-proof the Shack, we're going to have to do the next best thing. We're going to have to Bill-proof our minds."

I picked up the slightly rusted helmet of the mind machine and placed it on his head.

He kicked the chair absentmindedly. "So how do we keep Bill out of our minds?"

"Well, there's a number of ways. I personally had a metal plate installed in my head." I winced at the memory.

"Hehe. Good one."

I raised my eyebrows and banged my fist against the plate. "This machine is safer. It will scan your mind, bioelectrically encrypting your thoughts so that Bill can't read them. Now say hello to your thoughts."

I switched the machine on, and his mind was projected across the screen.  Most were average thoughts you'd expect the paranoid adolescent to have, but one was repeated over and over again: Wendy.  I raised my eyebrows.  Someone had a crush.

"Might wanna... ignore that last one..."

I internally smirked.  Type popped up on the screen: SCANNING THOUGHTS: 1%

This was going to take a while.  I pulled up a chair and laid my head on my arms.  I hadn't gotten much sleep since I got here... so... tired...