Mabel gasped looking over to see Dipper, whose eyes had gone wide as he fell backwards in shock. His body had just been hit with a paralyzing attack, but it seems that it did much more damage than their attacker had anticipated.
Their attacker, a Dream Demon by the name of Bill Cipher, laughed, tilting back as his one eye closed in mirth. He was completely oblivious to Mabel, who was kneeling besides her twin like her life depended on it. Bill apparently saw something wrong, so he stopped laughing, but his eyelids were just open enough to see as he fought back laughter.
"Oh, Shooting Star, you need to see the look on your face!" the Dream Demon laughed, his hands going around his stomach as he laughed harder. "You pathetic humans, always crying over silly things like death or destruction, but hey, that's life! If you can't handle it, well, then good luck kid!" He looked back at where the young teen was sobbing, and something hurt deep inside him that the usually bubbly young teen was in such a state.
It was unexpected when Mabel stood up, turning around to glare at the demon triangle. "You're wrong, Bill!" she yelled, but this only made it even more funny for the Dream Demon. "Dipper had a long life to live, and you took that from him! You murdered him! I bet it was because you aren't human, and that you don't understand the things we do! Why do you have to be so... so evil?" she was sobbing now, her hands flying to her face as tears streamed down her cheeks. Again, the demon felt a pang inside of him, almost like guilt. But he shrugged, placing his hand where his hips would've been, his eye looking down at her in a sarcastic tone.
"You humans, are lower than dirt. Not a single being I know would ever cry over these pity things like you do, Shooting Star. And, to see you even failed to defeat me without death. Heh! I guess I do bring destruction with me wherever I go. Well, I'll see you when the world is nothing but small, little pieces floating around space. In the meantime, I'll be watching you!" with a snap of his fingers, the demon was gone, and Mabel found herself staring at Dipper's body. What had happened, was no dream.
"Oh, Dipper!" she sobbed, falling to her knees and sobbing over her brother's chest. She felt no pulse, and that made her sob only harder. "Dipper, I'm so sorry! I tried, but I just... I couldn't..." Her eyes grew wide and the tears stopped as she wondered what she would tell her parents, or even worse, Grunkle Stan, about Dipper's whereabouts. She would be in so much trouble, she couldn't even look after her own brother. She stood up, her head hanging low, as she placed a hand on Dipper's chest, knowing fully well that the boy would never wake up.
She began to walk away, when suddenly, an idea struck her head. Even though Dipper was gone, she wasn't, so could she possibly take his place without anyone knowing? It's true, Dipper would look odd with her natural rosy cheeks and a lighter nose, but it was worth a shot. She stripped her brother of his clothing, changing into it like it was her own. It looked good on her, and she could pass off as Dipper easily... if she had shorter hair.
She quickly rummaged through her brother's pockets, searching for something, anything that could make her hair shorter. It was just her luck that she found a small pair of scissors in one of his pockets. She brought her hair over her shoulder, and hugged it one more time before she cut it short, like her brother's. The only thing left was the hat. She picked it up gingerly, a relic of her brother, and placed it atop her head.
"Don't worry, Dipper," she whispered, clutching the book to her side as she looked around the forest. "I'll avenge thee."
Bill Cipher might've expected Mabel or Gideon to summon him, possibly even Stan. So, it came as a big surprise when he saw 'Dipper' standing before him, The book at 'his' side and a determined look on 'his' face. Yet, something seemed... off. 'His' eyes were brighter, and the bags beneath them were gone. 'His' cheeks were a bit brighter, but other than that, everything was fine.
"Well, well, well, Pine Tree. You are alive, but how? I'm sure that the paralyzing curse I sent in your direction had you long gone, and Shooting Star was sobbing over your corpse. Where is she, anyway?" he asked, floating forward, his eye almost up in 'Dipper's' face. It came as even more a shock when Mabel, not Dipper, answered in an angry voice that made Bill's pupil constrict.
"I'm here to make you fall."