Song: 'Seven Devils'
So, you told me to update as soon as possible. That is what I did.
Enjoy.
Also:

KVLKOV ZIV KFKKVGH ZMW R SLOW GSV HGIRMTH.
(Use the Atbash Cipher to decode that and anything else in the chapter that might be coded.)

(And no, I didn't double check the coding, so some things will be spelled wrong.)

Now to the actual story:

They had thought it that Bill was dead. Mabel had been sure of it. Ford had said the demon had been killed by Dipper. So, how was that very demon speaking through her brother's mouth again?

"Well, well, well." Bill said gleefully, "The Pines family."

"Bill?" Ford exclaimed. "Dipper killed you, how are you--"

"Hahahahaha!!! Yeah, like Pine Tree could have ever done that!" He growled. "I hold his strings now. You can't do anything about it."

Mabel hugged Stan's arm even tighter. Had Dipper been Bill the whole time when he had returned? What if if had all been faked?

"Oh, relax, Shooting Star." The dream demon said. "I wouldn't be able to act that cheesy. Of course it was your brother."

Dipper's face split into a large, sharp toothed grin. "But hey, don't you like the changes I made? Quite the improvement, right?"

      "Leave Dipper alone!" Mabel screamed, running forward.

      "You don't think I want to?" Bill hissed. "But your idiot of a brother just had to steal my powers and now I'm stuck here! And it's all your fault! If he hadn't have wanted to see you again so badly this wouldn't have happened!"

"Wait, are you telling us that the kid did that to himself?" Stan asked.

      "Surprise, Fez!" Bill shouted. "You finally figured it out!" His face was twisted up in anger. The one golden eye on his forehead glowed even brighter.

      "Why would he do that?" Ford said.

      "Have you been listening, Six Fingers? Pine Tree was so desperate to get back that he messed everything up!"

      "What do you mean everything?" Mabel asked.

      The dream demon made a sound of annoyance. "ZIV BLF HGFKRW LI HLNGSRMT!?"

"What does that mean?" Stan said.

      "It's coded." Ford said. "We can't understand it."

      "Awe, is the Pines family confused?" Bill said. "Does Shooting Star need emotional support because her brother lied?"

     "Shut up!" She screamed.

      "Did you tell me to shut up?" Bill snarled. Then he laughed. "Look! Little Shooting Star is feeling left out!"

      "Leave her alone, Bill!" Ford said.

      "You don't control me, Six Fingers." Bill turned back to Mabel. "Do you know why it was always your brother and not you? Because shooting stars always burn up to fast and too bright."

      "Wha--?" She stumbled.

     "And Pine Tree knew that too. He's seen enough alternate realities and knows the future well enough. This isn't your only life. And while stars burn up quickly, trees smolder for much longer."

      "Leave them alone!" Ford pleaded again.

     "And you know what, Shooting Star?" Bill said, walking closer to her. "Even when pine trees finish burning, they leave their ashes. They can never leave. But they can watch many stars go out."

      Mabel had had it. It was one thing with Bill taunting her, but after taking her brother's soul and speaking through him, she couldn't take it.nPushing past the demon, she ran to Ford and wrapped her arms around him, refusing to let go. Her tears left trails down her cheeks.

      Stan approached the demon and poked a finger into his chest. "Listen up, demon, you have no right be insult Mabel. She's a good kid!"

      Bill just gazed at him, his one golden eye was heavy lidded with boredom.

      "Look Fez, you wouldn't understand everything. Even your own family hasn't told you everything." He smiled. "But if you ever want to make a deal Id b glad to--"

      "Like I would listen to you!" Stan growled. "Now listen, you leave my family alone and--"

      Bill lunged forward, wrapping his black, clawed hands around Stan's neck. Mabel's Grunckle froze in surprise. "Dipper, stop!" He gasped out.

      "Dipper isn't the one in control right now, Fez. Sorry." He tightened his grip.

      Just then a small blast shot through the air. A little zap of electricity hit Bill in his side. The demon dropped Stan and turned to Ford, who had his other gun out.

      "Leave them alone, Bill." Ford demanded. "And let Dipper go."

     "Why should I do that, Six Fingers?"

     "Because I said so, demon."

     "That doesn't convince me."

     "You know why, Bill." Ford said.

     "Oh?" Bill said. "Are you offering a deal, Six Fingers?"

     Ford ground his teeth and looked down for a moment. "Yes."

      "We'll discus this later, Six Fingers," Bill said. The gold eye glowed brighter. "It would be best if you didn't forget."

      "How could I?" Ford mumbled.

      Mabel tried to protest it, but Ford shook his head. "Do you want your brother back or not?"
      She didn't say anything.

     "However, Six Fingers," Bill added, "I'm not just going to give Pine Tree back." He smiled viciously. "It'll be a little different this time."

      "What? How?" Ford asked, alarmed.

      "You'll see, Six Fingers. Until then, Pines family!"

      Just as Bill was about to disappear, Stan stood up and punched him square across the jaw.
     Dipper opened his other two eyes. Mabel thought it looked weird when he had three eyes at the same time.

     "Ow." His voice also sounded weird because I was both Dipper and Bill talking at the same time. "Fez, what was that for?"

      "For being a jerk." He said. "And this one--" He punched him again. Dipper--or Bill--fell over, knocked out. "--Is for leaving Mabel alone for so long."

      Slowly, the golden eye on Dipper's forehead faded away. Now, he was just a piled heap, his wings splayed awkwardly to the sides.

      "Dipper!" Mabel said, running to his side. "Are you okay!"

     "He can't hear you, kid." Stan said.

     "Why did you do that?"

     "Well, he kinda deserved it, Mabel." Stan said, shrugging.

      "He'll be fine, Mabel." Ford said, looking at Stan. "Just out for a while."

     "Fine." She mumbled.

      "Common, let's take him inside." Ford added. "Stan, can you get him?"

     "Why should I be the one who has to carry the demon?"

     "Because you're the one who knocked him out in the first place!"

      Stan mumbled something under his breath as Mabel followed Ford to the Mystery Shack. She was glad she couldn't here it.

      "Grunkle Ford?" Mabel asked once they were inside.

     "Yeah kiddo?"

     "What was that deal you made with Bill about?"

     "Well, we never made a deal." Ford said. "You have to shake a demon's hand for that. The fire binds it."

     "But he'll be back, won't he?" Mabel asked, downcast.

      "Since when did Bill not show back up?" Ford said.

     Mabel didn't have anything to say to that, it was true. For once she wished that Bill would go and bother someone else.

     "So, Mabel." Ford began. "Is it okay if Dipper rests back up in the attic, in your room?"

     Technically, it was still their room. Mabel had refused to let them clean out everything Dipper had had. While he had been away, she had always slept in his side of the room.

     "Sure! That would be great."

     "Okay, that's good. We don't exactly have any spare rooms." Ford said.

     "Do you think Wendy and Soos will want to see him?" Mabel asked.

      "I think it's best to wait for that, Mabel." Ford said. "We don't know everything yet."

     "Okay." Mabel said. "But eventually?"

     "Sure."

    A few moments later and they were standing up in the attic. Ford motioned for Stan to bring Dipper in, and Mabel watched as they set him down gently.

     "It's almost lunch," Ford said. "I'll go see if there's anything to eat.

"Yeah, and I need to go take care of some things." Stan said as Ford left. "You okay here, Mabel?"

"I'll be fine." She said. Stan smiled and left. Did they really think Dipper was that dangerous? Frowning, she sat beside Dipper and waited for him to wake up. With wondering eyes, she gazed around the room. When her eyes fell upon the triangular, red window between her and Dipper's beds. An eye had been designed into the middle of it.

She had always wondered why so many things about the Shack were designed with triangles. Ford had built it before he knew about Bill, right?

"Triangles are the strongest structural shape." Said a voice.

She turned around and saw Dipper was awake. "Dipper! Your up!"

"Yes. Hello, Mizar."

"Um, who?" Mabel asked.

"I said Mabel, Shooting Star. Why?"

"I just thought you said something different, that's all."

"Oh, okay then." Dipper said.

"What happened with Bill, Dipper? I don't--"

"Shooting Star, don't call me that."

"Don't call me Shooting Star then! You sound like Bill when you do that!" She protested.
"Okay...Mabel... I won't."

"Thanks Dip!" She said, hugging him.

Protesting, he sat up. "I said to stop calling me that, Sho--Mabel."

"Well, what am I supposed to call you then?"

"It's... It's Alcor now, okay?"

AAAAAAAAAAAAAAHHHHHHHHHHHHHHHH!!!!!!!!!!
I'm fangirling over my own story, what has the world come to?!
GSV FMREVHV RH WVZW

I'll see you next chapter, HAHAHAHAHAHAHAHA!!!!!

(Also, self advertising here, go and read my Gravity Falls Ramblings book! You can request Bill to write chapters for you! Or me, but it's much more interesting when Bill writes.)

(Oh look! More self advertising! If you like terribly dark Weirdmaggedon AU fancifs with a whole lot of character deaths, pure evilness, a sad ending, Bill Cipher as a human, and Bill ruling over the universe and destroying the entire world, go read my story 'Change.' At your own risk of course.)

BYYYEEEE!!!
~Aza