Dipper Pines was sketching on the counter of the Mystery Shack gift shop. He was on register duty, but no one was even here. He looked down at the picture he had drawn of him and his sister together. Back when they were twelve, and had come to Gravity Falls for the first time. He'd give anything to go back to those days.
"Hey Pinetree!" Came a nasal voice from overhead.
Dipper looked up from behind the counter, shocked. "Bill?" He hadn't seen the demon in ages, not since Weirdmaggedon had ended years ago.
"Hahaha, miss me?" Bill asked.
"Umm, I guess." In truth, Dipper had been contemplating if he would ever see the triangle again. He had almost wished it so. "What are you doing here, Bill?"
"Looking for you, kid! How've you been?" Bill tipped his top hat a bit. At least he wasn't being outright malicious this time.
"I've been fine." Dipper looked back down at his picture. "How are you?" Best try to keep a normal conversation going.
"Wreaking havoc, as always!" Bill laughed. Then he looked back at Dipper, a bit suspiciously. "Seriously though Pine Tree, what's up?"
Dipper didn't answer. He continued to sketch.
"You know, I wouldn't have been able to come unless something was wrong. I see opportunity!" He rubbed his hands together and Dipper knew he was thinking of a deal. As if he could do anything.
"There's nothing wrong, Bill." Dipper said shortly. He tipped his hat down so Bill couldn't see his eyes.
"Say what you want, Pine Tree, but I know when something's up." Bill looked around at the empty gift shop. "Hey, where's Shooting Star?"
Dipper didn't raise his head. He stayed quiet, eyes focused on his drawing.
"Ohh, don't tell me." Bill said. Then he snickered a bit. "Nah, tell me." He looked at Dipper again, and spoke in the most serious voice Dipper had ever heard him use, "What happened?"
"She… it was a month ago…" Dipper eyes were filling with tears, but he refused to let them fall. "She passed, Bill."
"Wow, Pine Tree." Bill took off his hat. "That's a shame. I liked her."
"Yeah," Dipper said, gritting his teeth, "I liked her too." His hands were clenched at his sides. He had been trying to hold off his feelings about it, but it was too much. Mabel was gone. It had been at the beginning of the summer, when she and him were coming up for their annual trip to Gravity Falls. Only four days into their stay, she had gone off in the new car she and Dipper had gotten, and spun off the road. Their parents had come up for the funeral, but Dipper had requested to stay in Gravity Falls for the remainder of the summer. He barely talked to anyone. Wendy was staying at Oregon State for the summer semester. Stan and Ford both left him alone, and Soos was so torn up that he hadn't come to work in weeks. He had been so alone this summer, that Bill was almost a welcome sight.
"You're considering something, aren't you?" Bill said. Dipper turned away from him. "You know I can help, Pine Tree."
"How could you help?" Dipper knew he couldn't trust Bill, but he couldn't help looking at him curiously. He'd do anything to get Mabel back.
"You know what I can do." Bill said, "I see several options. Either you can join her, or she can join you."
Dipper looked up sharply. "What do you mean, she can join me?"
For once, Bill looked hesitant. "Well, it's quite forbidden. Your uncles wouldn't like it. But I do have access to powerful stuff."
Dipper wiped his eyes with the back of his hand. "I don't care if Stan or Ford would like it." Both of his uncles had been distant with him since Mabel had gone, and it wasn't like he couldn't make his own decisions. "Tell me, can you bring her back?" He stared up at Bill desperately.
"Not exactly. No one can do that. But I can give her a vessel to re-enter this world." Bill thought. "But I would have to find her first."
Dipper bit his lip thoughtfully. "What would you want in return?" He would give just about anything to have his sister back.
Bill looked at him appraisingly. "I'm not sure yet, Pine Tree. Ever since you stopped my Oddpocalypse, I've actually been a bit aimless." Bill rolled his eye annoyedly. "I'm sure you'll be glad to know that Sixer's plan to seal the rift forever is extremely effective." He thought a moment. "How about you'll owe me a favor, huh? A service of my choosing at any time in the future."
Dipper looked at his hand, trying to decide. Could he trust Bill? What would he do to bring Mabel back? But then again, did it really matter? As long as he got to see her and talk to her again…
"Deal." Dipper said, holding out his hand.
"Good choice, Pine Tree." Bill took his hand as a bright blue flame encased the handshake, sealing it.
"Now give me a second, kid. I've got to find her. She could be anywhere. But it'll probably only take a few minutes in your time." Bill vanished.
Dipper looked down at his drawing excitedly. Was he really going to see her again? The past month had been the longest of his life. He never considered how lonely he'd be without his twin. She had always been by his side.
And now she would again.
Bill reappeared above Dipper, holding something that Dipper couldn't see.
"She's here, kid. I don't suppose you can see her, but she's quite confused." Bill snapped his fingers. "Now give me your hand, Pine Tree."
Dipper slowly extended his arm toward Bill, slightly afraid of what he might do.
Bill grabbed Dipper's hand and spread his fingers apart. "Now this is gonna hurt." He said, tracing complicated patterns on Dipper's palm. A star glowed faintly blue on his hand, burning him slightly.
"I'm going to transplant her into your body. You can join me in the Mindscape."
Dipper nodded. At least Mabel would be okay.
There was a sudden blue flash, and Dipper felt his soul being ripped from his body. A moment of burning pain, and then he felt nothing. He opened his eyes to see his body laying on the floor. He looked down and saw that he was incorporeal again, much like he had been the time Bill had inhabited his body.
"There." Bill said, panting slightly. "She'll be unconscious for a bit, but she's in there." He looked sideways at Dipper, floating next to him.
"Bill?" Dipper asked, looking back at him.
"Yeah, kid?" Bill said, looking uncharacteristically serious.
"Is there any way that you would make her forget that she died, or that I made a deal with you? I'll… I'll owe you two favors." He said desperately.
Bill sighed. "Life is a tricky thing to play with. She's going to know exactly what happened. And let me tell you this: You can reclaim your body at any time, but when you do, she'll be gone. Back to where she was before." He shook himself, and it seemed that he was trying to recover his usual sassy bravado. "Other than that, you already know the rules of the Mindscape, don't you?"
Dipper nodded. "Thank you, Bill." He wondered why the demon was suddenly being so generous. He could only imagine what Bill would ask of him later, but any price was worth it.
"Don't mention it, Pine Tree. Remember, for now, you're mine. That was a big thing I just did, so the moment I call on you I'd better get an answer. Got it?"
"Yeah, I understand." Dipper said, already floating down next to his body, where he knew Mabel would soon be returning.
"Great. See ya, kid. Have fun when she wakes up."
Dipper was sitting next to her, intangible hand on her shoulder. "Oh gosh, I'm gonna be a dead man." He bit his lip again, wondering how Mabel would react to this.
"You already are, Pine Tree!" Bill laughed.
Dipper rolled his eyes. "Freaking flying Dorito."
"Hahaha, I'll be watching kid." And Bill disappeared.
Suddenly Mabel began to stir, her eyes opening the tiniest bit. Dipper looked down at her, smiling sadly. "Heh… Hi, Mabel."
"Ugh… Dipper?" She opened her eyes and sat up, rubbing her face.
"H-how are you feeling?" Dipper asked, ecstatic that it had worked, and yet scared of her reaction.
"I feel weird… Where are you? I can't see you…" She suddenly seemed to come to herself. "Wait, how am I here?"
"Heh, surprise?" Dipper said timidly.
"What did you do? I- I was gone, but…" She shook her head. "Where are you?"
"I made a deal with Bill to bring you back. I guess you can't see me though, I'm right beside you."
"You WHAT?" Mabel looked at herself. "Wait, am I you now?"
"That was one of the conditions. You're in my body. Bill needed a vessel to bring you back and I… Well, it's like when Bill possessed me but instead, it's you."
Mabel stood up, wobbling a bit and leaning against the counter. "But I don't want this! Dipper, you should have just let me be!" Dipper stayed silent. "I know it's hard, but you have to move on!"
Dipper looked down, ashamed. "I- I'm sorry, Mabel. I just wanted you to come back."
"Dipper, I know you don't want me to be gone, but please don't give up your own life for me!"
"I'm sorry…" Dipper repeated softly. Tears were sliding down his face from both joy and grief.
"Where are you, Dip? Are you in front of me?" Mabel asked, looking around.
Dipper nodded, then remembered that she couldn't see him. "Yeah, I'm in front of you."
Mabel looked straight at him, right into his eyes, even though she couldn't see him. "Can you fix this?" She asked softly.
Dipper adjusted his hat. "Yeah, I can. I can go back into my body, but you'll be gone. For good this time."
Mabel continued to look into his eyes. "I want you to do it, Dip. Send me back. I promise it's not the end. I'll still be here, somewhere. Remember grandpa? I saw him, Dip. I know him now. You have to go on without me. But I'll be here when it's your turn. Okay?"
A single tear slid down Dipper's face. "I love you, Mabel."
"I love you too, Dipper."
Dipper hugged her, even though he knew she couldn't feel it, and melted back into his body. He thought he heard a faint "Goodbye…" as he opened his eyes to the empty room. He fell to his knees, sobbing. He sat there for a long time, face in his hands, until the tears subsided.
"Geez, Pine Tree." Came a voice above him.
Dipper jumped to his feet, wiping away any remaining tears, to see Bill over him again, arms crossed.
"That didn't last long." The demon remarked.
"I had to let her go." Dipper said.
"Was one last conversation really worth anything you could give me?" Bill asked loftily.
Dipper looked up at him and nodded. "You wouldn't get it." He turned away.
Bill raised his eyebrow. "Wouldn't I, Dipper?"
He turned his back on the demon. "Just forget it."
"Huh. You're more like me than you know." Bill said.
Dipper looked at him, confused. "How?"
"How do you think I got like this? What I don't understand is why you let her go again."
"She wanted to go. I'd rather know she's happy and not see her than to have her here unhappy. She didn't want to be here." He clenched his fists, voice rising. "You think I wanted to let her go Bill? Do you?! I wouldn't have made the stupid deal if I knew from the start I would end up letting her go. But I love her, so yes, I let her go Bill!" He shouted.
"Relax, kid. I guess you've got more guts than I thought."
"Yeah, time changes you when you're mortal."
"Yup. Sucks, doesn't it?" Bill said lightly. Dipper turned away again. "You know kid, you'd make a good apprentice. Remind me to tell you some secrets sometime."
Dipper adjusted his hat. "Sure, whatever."
"Hm. You'll come around. Anyway, see ya! Remember, you still owe me that favor!" And Bill disappeared again.
Dipper looked down. Mabel was dead. He had to be strong and accept that. But she was still out there somewhere, and now he knew he would be with her again someday. He took the picture he had been drawing and put it in his pocket. He would hang it on the wall in his bedroom.
He knew Mabel wouldn't want him to keep sulking. He had to move on, live the life she would want for him. So he strode out the front door and into the sunshine, ready for a new adventure.
*This was based on a lovely Shamchat I participated in. Thanks a ton to the person who did it with me. I am contemplating a sequel, to do with the favor Dipper now owes Bill and Bill's backstory. Tell me what you think!*