Reverse!AU. I was inspired to write this based off a picture and a head canon off of Tumblr. The head canon was mainly about how it could be possible for the Gleeful Twins to turn into demons depending on how much they use their amulets. The picture itself was of Mabel, so I'm going with it.
Warning! This will contain blood and gore and so on. If you're against that and prefer not to read it, I encourage you to go and click on another amazing story.
I don't own Gravity Falls, the head canon, or the cover image.
Are You Afraid of Me?
The signs had been small and hardly noticeable at first. Her teeth were a bit sharper and sometimes her eyes would flicker to where her pupils were mere black lines and she had no irises, and her sclera was blue.
Sometimes in her sleep, she'd mumble words in a language Dipper was unfamiliar with. Then, he had just deemed it nonsense and gibberish. Now, he wasn't even sure.
It was easier to upset Mabel and harder to calm her down.
Usually, when she was upset, the promises Dipper made her of revenge on their enemies and ending said enemies' pitiful lives with slow, painful, gruesome deaths was enough to calm her down.
When the changes first started, she had deemed that the promises of revenge weren't enough.
Mabel had become even more sadistic than usual.
In the morning, Dipper would sometimes awake to find her bed empty. Sometimes, even the window was open.
On those days, she'd come back, march up to their shared bedroom, and hardly come out of her room, let alone talk to anyone.
Not only was she becoming more distant, but her strange behavior made Dipper worried.
But tonight, Dipper had a plan.
He would only act as if he were asleep. When Mabel woke up and went off to…wherever she went…he'd be ready to follow her.
Sure, it wasn't his best plan, but he didn't care. He had to know what was wrong with his sister. Then, maybe, he could help her get through it.
Dipper turned off the lights in the room he shared with Mabel and went to lay down on his bed.
As he did, he saw Mabel standing in front of and gazing out the window, unblinking and still.
''Mabel?'' he asked her, effectively snapping her out of her trance.
She looked from the window over to Dipper. ''Yes?''
''Are you alright?'' he asked her, voice laced with concern.
''I'm quite fine.'' She responded, her gentle, odd tone of voice making Dipper shiver as it filled the still air.
She moved from in front of the window, her spaghetti strap, aqua blue gown fluttering gently and flowing behind her. She laid down in her bed, pulling up her silk sheets over her body.
''Goodnight, brother.'' She whispered gently, turning so she was facing the wall and not Dipper.
He frowned at that, but complied. ''Good night, sister.''
He closed his eyes, acting like he was asleep.
He didn't know how long he was like that, but staring at your eyelids got old.
What seemed like hours later, or it what might've actually been hours later, Dipper heard the gentle rustle of Mabel's sheets and felt a breeze flow over him.
He acted like he was tossing and turning in his sleep, rolling over so he was facing the window.
He felt her pause, her eyes scanning over his body.
Moments later, she opened the bedroom window and leaped out, the bright light of her amulet starting.
Dipper opened his eyes once she left, jumping out of bed and rushing over to the window.
He watched as she ran and disappeared into the trees, her hair blowing behind her wildly.
He hadn't thought of how he would get down from the house as quickly as she did, but he also hadn't been sure she jumped out the window nightly and didn't just use it as an entrance back in to avoid suspicion.
He was about to curse himself for letting her get out of his sight, too, but didn't as she saw her fly into the air.
Blue swirls circled around her and Dipper noticed something completely different.
Sure, they had levitated before in their performances, but this was different.
Attached to her back were bat-like wings. They were hardly wings, though, but more of just an outline of bat wings, glowing the same shade of green-blue as her amulet.
He watched with peaked interest as her gown went up in blue flames, revealing a different outfit underneath.
She still adorned her signature headband, and amulet, but the headband was black, cyan blue lined on the sides. Along with that, she wore black leggings, black leather boots, and a black and cyan blue dress. The dress was black on the back and sides, while the center was cyan blue with six black buttons. The sleeves went down to her elbows, with cyan blue cuffs, and a black collar to the dress, complete with the tent's star on the collar and black gloves.
Her laugh filled the night. At first, it sounded like her normal, stage ready, bubbly laugh. But then, it turned into a dark, psychotic laugh that sent chills down Dipper's spin.
Her wings flapped behind her as she swopped down back into the trees. Dipper rushed down the stairs to the front doors, swinging it open and slamming it shut.
He looked around wildly and listened carefully for Mabel.
He heard her dark and psychotic laugh once more and ran to find where she was.
He saw her fly above the trees one more time, followed by her disappearance.
He ran through the trees, then stopped once he saw her flying just above the town.
She was searching the streets, which only had a few people on it. The lights glowed faintly, just barely illuminating the streets.
He found himself running once more, stopping just before he ran into town. That would draw unwanted attention, which would garner Mabel's attention.
He watched Mabel as she dove down to the streets, picking up one person and muffling their scream with her gloved hand.
On closer inspection, Dipper saw it was a boy, maybe sixteen or seventeen by the looks of it.
Mabel flew back into the trees, landing in a clearing and dropping the frightened teen.
Dipper watched from behind a tree as Mabel gazed down at him.
''Why so afraid?'' she asked, tilting her head. ''Don't you know who I am?''
''Mabel G-Gleeful?'' The boy stuttered.
Mabel smiled, revealing a sharper set of teeth.
''N-No.'' the boy crawled back away from her. ''You're n-not her. You're a m-monster!''
Mabel's smile vanished as she placed a look of mock hurt on her face.
''How rude.'' She stated, eyes narrowing in anger.
Her eyes then lit up as her smile reappeared back on her face. ''Good thing for you, I prefer feisty prey.''
The teen bit his lip. Mabel walked forward to prevent him from escaping.
''Hmm.'' Mabel hummed in thought. ''However, you're not that brave.''
Before Dipper could even register it, Mabel was on top of the boy, hands driving in his stomach repeatedly.
The teenager screamed in pain as he tried to crawl back again.
Dipper watched in utter horror as the boy's guts spilled and his blood soaked the ground.
Mabel threw it aside as she kept digging until the boy's stomach and chest were all clawed out. The boy fell back, dying as he eyes shut for the last time.
Mabel stopped, panting with a sadistic grin on her face. She cupped his blood in her hands and drank it.
When she was done, she wiped her mouth on the back of her gloves, licking her lips in satisfaction.
A glowing, yellow ball of light began to lift itself from the boy's corpse and float to the heavens. Mabel smiled as she got up from her knees and caught the ball in her hands.
The ball warped and turned blue. Mabel lifted it to her mouth and breathed it in. The ball of light spun and grew smaller as Mabel continued to breath it in. Soon, it was gone.
The color from Dipper's face was gone as he turned to run.
Instead, fate had other plans. He stepped on a twig and it snapped underneath his foot. He froze, eyes wide like a deer caught in headlights.
Mabel immediately stopped, raising her head and sniffing the air. She looked in his direction as Dipper jumped behind a tree.
Lucky for him, Mabel hadn't seen him.
''Come out, come out, wherever you are.'' She hissed in a sing-song voice, getting up and walking around the clearing.
Beads of sweat traveled down Dipper's face as he tried to quiet his breathing.
''I know you're here.'' Mabel drawled.
Dipper turned from the tree so he could see her, but she wasn't there. He sighed in relief.
He let his guard down too soon.
Mabel appeared in front of him, upside down and staring at him right in the eye.
''Dipper?'' she asked, tilting her side slightly.
Dipper didn't respond.
Mabel jumped down from the branch she hung from, landing on her feet, her wings folding up.
''What're you doing here?'' she asked curiously, her eyes changing.
Her pupils were now mere black lines, without irises and her sclera was now light blue.
''M-Mabel?'' Dipper breathed. ''Why…why are you out here?''
''What do you mean?'' she furrowed her brows.
''Murdering innocents?!'' Dipper said, motioning towards the decaying body.
''They were unimportant.'' Mabel stated simply.
''That doesn't mean you have the right to kill them!'' Dipper's right eye twitched with irritation, losing some of his fear.
No denying it, Dipper loved a good kill. But the fun was taken away when they didn't even try to fight back or he didn't have a reason to kill them in the first place.
Mabel stared at him, narrowing her changed eyes and looking him up and down like a predator with its prey.
''Do you not remember, brother?'' she hissed sharply. ''The promises of revenge and murder? The slow, painful, gruesome death?''
''I-I…'' Dipper didn't couldn't find anything to say. He had promised her that.
Mabel laughed at his speechlessness. That same dark and sadistic laugh.
''Brother.'' Her voice warped, becoming darker and more like a…
Dipper's eyes widened as realization struck.
A demon.
''Mabel, this…this isn't you.'' He slowly backed away from her.
''What are you talking about?'' her voice warped back into her own, before going back to the way it was. ''This has always been me. This is who I am.''
''No, it isn't.'' Dipper gazed into her changed eyes. ''I've known you for your whole life. This has never been you.''
''Who are you to say!'' she growled at him, her nails seemingly growing sharper.
Dipper backed away a bit more as Mabel's pupils disappeared entirely, leaving her eyes plain blue.
''Mabel, I-'' he stopped talking when he saw her amulet begin to glow.
Mabel had always used her amulet more often than Dipper did.
The entire reason they had their amulets in the first place was because of the journal they held in their possession. The twins had traveled around forever, having to talk to different people who had known about the mysteries of Gravity Falls. A little charm here and persuasion there, and the amulets belonged to them.
But thinking back to the journal and reading about the amulets, Dipper remembered that if the amulet was overused, it came with terrible consequences to the owner.
This wasn't what he had imagined.
His thoughts were cut short when Mabel grabbed his attention.
''What, brother?'' she asked him, baring her teeth.
''Your amulet did this to you.'' Dipper stated, blinking at her in realization. ''It turned you into some sort of demon!''
Mabel laughed harshly. ''Demon? Why, no.''
She laughed once more before she continued. ''Brother, I've seen what this amulet is capable of. I know the secrets of Gravity Falls, and I have power beyond comprehend.''
''Mabel-''
''You've said it yourself, we have this town in the palm of our hand. But now, we can rule it!'' she smiled a toothy smile, her sharper teeth flashing in the light of the moon.
''Dipper.'' She offered a hand to him. ''Join me.''
''W-what?!'' Dipper yelped. ''No!''
Mabel growled. ''Those who are not with me are against me!''
Before Dipper could respond, Mabel tackled him to the ground, her claws digging into the palms of his hands.
Her eyes glowed as she leaned down over him, pinning his arms beside his head. Dipper squirmed underneath her.
Her face was now mere inches from his own, her teeth bared threateningly.
''M-Mabel!'' Dipper cried in a desperate attempt to get to her. ''I-I've never been against you!''
He felt her grip on his wrists weakening, but she still leaned over him, her eyes unchanging as she hissed at him.
''Silence!'' she shouted at him.
Seeing that he was getting to her, Dipper kept going.
''Mabel, I know you're in there! I know you don't want to do this!'' he cried.
''I said silence!'' her hands moved from his wrists to around his neck.
Dipper grabbed her hands before she could wrap them around his neck and flipped them over so he was on top.
Mabel fought against him as Dipper pinned her hands down.
''Mabel, come on!'' he said. ''Please!''
Her eyes flashed to her own for a second, before morphing back into their previous state.
''Stop!'' she yelled. ''S-stopi-it!''
Her voice warped in between Mabel's and the demon's.
''No!'' Dipper said. ''Mabel Gleeful, I know you're in there!''
Mabel screamed out in pain, her eyes squeezing shut and her squirming becoming stronger.
''Mabel!''
Her eyes snapped open, still glowing blue as she growled and kicked him off.
Dipper slammed into a tree, before falling to the ground.
He groaned and sat up, rubbing his head. As he opened his eyes, he saw Mabel on her knees.
She still screamed in pain, tears streaming down her face from her closed eyes.
He ran over to her, placing a hand on her shoulder.
''D-Dipper?'' Mabel's own voice came back as she whimpered.
''I'm here.'' Dipper assured her. ''Come on! You can do this!''
Mabel screamed once more, her hands clamping on either side of her head as she shook violently.
''I…I can't see.'' She bit her lip.
Dipper decided mentally that it wasn't the time to ask what that meant given the situation.
''Dipper?'' she asked, her voice shaking unevenly. ''W…Where are you?''
Dipper knelt down in front of her, placing both of his hands on her shoulders.
''I'm right here.'' He said, shaking her gently. ''And I'm not going anywhere. Come on, Mabel! Fight this!''
The wings folded on her back dispersed as sparkles went up into the air, as if ashes rising from a fire.
The demon's voice came through as it hissed out of Mabel's mouth, revealing her sharpened teeth once more.
''You can't stop me! She's mine!'' Mabel opened her eyes, which once again glowed blue as she glared at her brother.
Mabel reached a clawed hand out towards him as he let go of her and crawled away.
''D-Dipper.'' Mabel's voice came back, quavering. ''D-Don't leave me.''
A smile spread across her face, replacing her previous look of pure helplessness.
Her clawed hand nearly got to his throat when her other hand grabbed her wrist.
The demon drew in a sharp gasp as Mabel yanked her own hand back.
Dipper had to admit, watching Mabel struggle against herself was weird.
The feeling was cut short, replaced with horror as Mabel looked up at him.
It seemed as if her face was split into two sides, each showing the same emotions, yet seeming opposite at the same time.
One of her eyes was the demon's, but the other was her own. One corner of her mouth tilted down and showed sharp teeth bared in frustration, while the other side was almost the same, just without the sharpened teeth.
Frustrated tears built up in Mabel's eye, but the other narrowed in anger.
''Enough!'' Mabel cried out, using her hand to yank her headband off.
She smashed it on the ground, the amulet shattering completely and wisps of blue and green flowing through the air.
''NO!'' the demon screeched, using the rest of its strength to make Mabel crawl over to the shattered remains.
She picked up the scattered pieces, clutching them to her chest.
''What have you done?'' the demon seethed quietly.
''What I had to.'' Mabel answered.
A greenish-blue aura surrounded Mabel's body as she stood up, a clawed hand reaching out to Dipper once more. This time, it was able to reach him and wrap around his neck, its claws digging into his flesh. Dipper screamed, before he felt her grip loosen completely and she let go, releasing Dipper. Dipper fell to the ground, taking in deep gulps of air, hacking and coughing.
He turned his head up to Mabel, who stared down at her hands, her teeth bared in fury. The aura surrounding her went up in flames, rising up into the night sky.
Once it did, Mabel's eyes returned to her own, rolling into the back of her head as she fell to her knees.
Dipper jumped to his feet, rushing over to catch her before she hit the ground.
He cradled her gently.
''Please…'' he whispered. ''Come on, Mabel, wake up.''
Mabel's hand fell from her chest, her open palm facing upward as a few shards of her shattered amulet rolling to the ground.
''Mabel, please.'' Tears were forming at the edge of his eyes, a few already slipping down his cheeks.
He held Mabel tightly as he cried.
He stopped abruptly when a small laugh came from underneath him.
He looked down at Mabel, whose eyes remained shut but her lips curled into a smile.
''Heh. Guess a demon can't even drag me down.'' Mabel chuckled, her eyes still closed.
Dipper squeezed her tightly in a hug, which caused Mabel's eyes to snap wide open.
After a few moments, Dipper backed away from the hug and looked down at her.
''Don't worry, brother.'' She gave him a reassuring smile. ''I'm not going anywhere.''
Dipper wiped away his tears with the back of his hand.
''Hey, we're still twins forever.'' Mabel said, sitting up. ''Remember?''
''Yeah.'' Dipper smirked. ''I remember.''
''Besides, you were right when you said I was using that amulet too much.'' Mabel rolled her eyes. ''It's gone, now.''
''Yes, but it amplified your powers.'' Dipper said seriously.
''What will we do about that?'' Mabel asked, furrowing her brows.
''I can get you a new amulet, but unless you can learn to control that demon and summon it at your will, you can't use it as often.'' Dipper explained.
''I can try, but I'm afraid I can't make any promises.'' Mabel folded her arms.
''Alright then, I'll get you a new amulet.'' Dipper said. ''But honestly, I'm tired.''
''Yeah.'' Mabel agreed. ''The entire demon thing really took it out of me.''
Dipper offered her his hand. ''Let's go home.''
XXX
The next day, Dipper had gone off to get Mabel a new amulet. Mabel herself had stayed behind to handle some…business.
The summoning circle she prepared glowed as she held the journal in one hand.
She looked over the page of the journal and decided that she was ready.
She stepped forward, inhaling deeply before letting it out.
Citing a spell from the journal, her eyes glowed a light blue and wind pushed throughout the room.
Her hair flapped wildly around her head and shoulders, the journal falling from her hand.
She was forced to her knees, her hands holding her sides as if trying to contain something within.
When Mabel felt the energy pulse throughout her body and felt like she couldn't contain it anymore, her hands fell, stretching out to her sides.
The next words of the spell were said backwards, but her mind was so jumbled with the searing pain and energy she felt coursing through her that even she couldn't comprehend what she was saying.
All she knew was that time stopped as the world took on a monochrome color.
Mabel collapsed, panting heavily as she looked up.
A bright flash of light flooded the room, followed by someone who looked like her.
''WHO DARES SUMMON ME!'' Her own voice bellowed, but it echoed in the room.
The demon looked at her surroundings, realizing where she was.
''Oh, it's you.'' She inspected her nails. ''Finally ready to deal with your own demons?''
''I have something that might be of interest to you.'' Mabel said. ''And you weren't my demon in the first place.''
The demon laughed. ''Yes, but you see, you were my last host.''
The demon folded her arms. ''I possess the form and knowledge of my host until I get a new one. You know that. I was trapped inside that cursed amulet until you formed a bond so strong with it that I was able to move in and out of your mind as I pleased. That is, until your brother got in the way.''
''And I'm glad he did.'' Mabel glared at the demon sharply. ''But now, I have an offer to make.''
''Oh, really?'' the demon smirked.
''Yes.'' Mabel answered her. ''If we can form some sort of bond or alliance, I'll give you permission to move in and out of my body and mind as you please.''
''A physical form without harassment?'' the demon raised an eyebrow.
''Yes.'' Mabel responded. ''But we would work together. I've a few…problems I need taken care of.''
The demon's smirk grew into a full-on smile, showing off her sharp teeth.
She offered her hand, which became engulfed in greenish-blue flames.
''Do we have a deal?'' she tilted her had to the side, blinking at Mabel with her inhuman eyes.
Mabel took her hand, shaking it. ''Deal.''
Alright, then! I think I might leave this as a one-shot for now, but if I get enough reviews saying they want me to continue, I will. So please, comment and review.
And I'm not placing an OC in the story. Think of her almost like Bill Cipher. Almost. But she's more of a personal demon to Mabel considering she formed a strong bond with her. So just think of her as one of Mabel's demons.
I repeat, she is not an OC.
Anyways, thank you for reading.