Here's a oneshot of Dipper seeing his biggest fear! Bit over dramatic, but meh. Can you blame him? After Wierdnagetton. During Harry's what is it... third year? Yeah, third year, I think.

Oh well. I'm sure you guy's want me to stop wasting time. If you have questions, read the bottom AN.

So! Without further ado, here's my story!

Dipper stood nervously in line for the Boggart, Mabel right behind him.

Dipper didn't know what his biggest fear was. He has so many. Would it be a monster? His family dead? Maybe being caught singing 'Disco Girl'…?

Lupin smiled with a twinkle in his eye and motioned for Dipper to step up. Dipper never was good at magic. Especially under pressure. Mabel was better at it than he was. She always seemed to manage to get every spell right without even trying. But Dipper studies harder. He knew all the facts about magic. Now if only he could get his wand to cooperate…

Mabel gave him a gentle nudge. He hadn't realized that he had been holding up the line. He stepped forward nervously. The Boggart swirled and swirled until finally settling on a creature Dipper knew all too well. A creature he never would have thought to see here in the classroom of Hogwarts, of all places.

"HIYA' PINE TREE! DIDJA' MISS ME?"

Dipper yelped and stumbled backwards. Every eye was on him now. The students were too stunned by the strange demon to react. This was not your average fear.

"AWWW, YOU DID MISS ME!"

Dipper raised his wand with a shaking hand, "Ridd-Riddikulus! Riddikulus!" Bill lazily dodged the shots.

"C'MON PINE TREE. YOU CAN DO BETTER THAN THOSE TOOTHPICKS!"

"Wh-what are you doing here, B-Bill?"

"I CAME TO FINISH OUR DEAL. YOU PROMISED ME A PUPPET, AND YOU DIDN'T KEEP YOUR END OF THE DEAL."

"Y-Yes I did! I have the sc-scars to prove it!" Dipper rolled up his sleeves to reveal fork marks running up and down his arm.

"I WANTED A LIFE-LONG PUPPET, PINE TREE. YOU BARELY GAVE ME AN HOUR."

"Then why are you still standing h-here? If you're going to do it, j-just get on with it already," Dipper spread out his arms and closed his eyes, waiting for the inevitable to happen.

"AHAHAHAHAHA! YOU MEATSACKS ARE HILARIOUS! ALMOST AS FUNNY AS PAIN! THE THING IS, PINE TREE, I CAN'T TAKE THE SAME PUPPET TWICE. I GET TO PICK AND CHOOSE." Bill looked over the swarm of confused children. A few of them shot spells, and Bill simply moved to the side. Professor Lupin tried to intervene, but Bill simply waved his hand and Lupin was telepathically pinned to the wall.

Dipper glowered, "You leave them out of this, Bill. This battle is between you and me."

"OR MORE SPECIFICALLY, YOU, ME, AND SHOOTING STAR," Bill said with a twinkle in his eye.

Sudden realization dawned on Dipper, "No…"

As fast as lightning, Bill skyrocketed toward Mabel. Before she had time to react, she doubled over, and when she looked up, her eyes were yellow. Mabill smiled and licked her teeth, "PAIN IS HILARIOUS, PINE TREE. BUT THE BEST KIND IS WHEN IT HURTS YOU MORE THAN ME."

Finally, a student got a hold of his senses and stepped in front of Mabill. Mabel collapsed and a swirling form came out of her and formed a Demeantor. It lashed at the student, but Lupin (who was now free of Bill's telekinesis) shot a spell at it, "Riddikulus!"

It changed into a flower and with a flick of a wand, it was shot back into the cabinet.

Lupin instantly checked on his startled students, "Is everyone alright? Is anyone hurt?" He checked on Harry, gave him some chocolate, and then cautiously moved to Dipper. Mabel was by his side, giving him hugs and whispering comforting words to him. Lupin moved a bit closer and heard the whispers.

"Sh, sh. It's okay, Bro-Bro, I'm fine. Bill can't hurt me. He's back in Gravity Falls."

"But he can h-hurt you Mabel. He'll find a way. A l-loophole. You know him. He always does."

"He can't hurt me. Bill can't get into Hogwarts."

"But he gives me nightmares, Mabel. Terrible, terrible n-nightmares…"

"I know, Dipper."

"I kill everyone, Mabel. He m-m-makes me. Then when I wake up… and nobody's there…" The boy broke off in silent tears. Every student was now staring at this mysterious duo. Mabel ignored them, and Dipper blushed deeply.

Lupin kneeled next to Dipper and placed a hand on his shoulder, "Dipper, who was that?"

Dipper shook his head and tried to burry himself beneath his robes.

Lupin sighed and looked at Mabel. But she also shook her head sadly, "You don't need to worry about Bill. Dip-Dop and I made sure of that."

Lupin eyed her questionably but decided to drop it for now. He would confront Dumbledore about this later. "What do you think would be best for your brother right now?"

Mabel eyed her brother up and down, "Sleep, probably."

Dipper started to shake like a leaf, "No, Mabel. P-please… don't make m-me… I can't sleep. He's w-watching me Mabel. Always watching…"

"But Dipper, you haven't slept for days." Only then did Lupin notice the dark bags under his student's eyes.

"No, I c-can't sleep. B-Bill hurts me, Mabel. He tor-tortures m-m-me."

Mabel bit her lip, "Do you have something for dreamless sleep?"

Lupin nodded, "There's some in the Hospital Wing—"

"I'll take two."

Lupin eyed her questionably.

Mabel shrugged, "Dipper isn't the only one Bill likes to play with."

With that, she helped the sobbing Dipper up and led him out the doors, ignoring the eyes of the other students. "C'mon Dipper. There's medicine we can take. It'll keep Bill out. We'll be able to sleep tonight—" the door slammed shut, and every eye turned to Lupin. But Lupin was just as confused as they were. The twins never shown signs of issues such as these. Well, sometimes they seemed sleepy in the mornings, or whispered to each other secretly. But all students did that. He ran his hand through his hair, and finally decided on a suitable answer that would make everyone happy.

"Class dismissed."

Poor, poor, Dipper. I think he's been through something rough.

If you're confused, read this:

- In this sorta' AU crossover, Dipper and Mabel banished Bill to another dimension. But he still likes to torture the Pines' family in their dreams.

- Bill can only directly change the dreams for his own enjoyment to the people on the wheel.

- Though Bill tortures Mabel, he's hardest on Dipper and Ford. He visits them the most often and gives them the most attention out of everyone. So that's why Mabel isn't as affected.

- Dipper is in Slytherin, Mabel is in Gryffindor. And that's why Dipper says "no one is there" when he wakes up.

- Though it's not official, Mabel's fear might be Bill too, and that's why Bill didn't change when he possessed her.

- Boggarts seem to have a very loose outline of the thing they mimic, so that's why boggart Bill was able to possess Mabel. Just like boggart Dementors spread fear and sorta' suck out Harry's soul.

Man, that's a lot of stuff for a one-shot. I just don't want to PM anybody answers. If you guys can come up with an actual question that's not above, go ahead and ask. Otherwise I might just ignore you.

So anyways, check out my other stories. I'm trying to figure out which story to write next, so you can see the options at the end of chapter nine in my Beo Caldez crossover. You can vote if you feel like it.

Flames are appreciated, but if you do, make sure it's constructive. I try to make sure I write my stories the best way I can. So if there's something really bugging you about this, tell me why, where, how, and what to do different. And if you guys really want it, I may continue this.

So anyway, Favers and Followers are great, but Reviewers are my favorite! Review!

I own nothing but this story. I no way am I claiming claim over Gravity Falls or Harry Potter. Those belong to their creators and owners.