Dipper kept yelling, in darkness. There was nothing to do, but yell, scream. He couldn't get out, he couldn't see. It was dark, and cold, but his throat never seemed to hurt, and he wasn't hungry, or thirsty. He was perfect... Except he was alone. "MABEL!" he called again, tears seeping into his voice.
Again, silence, except for his own echoing voice.
He began to cry, and his form slowly began to change.
Time passed quickly. Not that he had anything to tell time with. There was no light down here, except for his own. The light he cast whenever he wished to, and could dim as he wished. He could shine a variety of colors, effortlessly.
He wished it wasn't so. He would have given this newfound power for something to do, to practice, anything. There was nothing in this cave, nothing at all, and after yelling for what seemed like forever, he began to realize he wasn't going to be heard.
Bill had tricked them, it dawned on him. Bill had betrayed him and Mabel, just so he could get out of the cave.
But Dipper understood now. The cave was horrible. Small, confined... He felt power brewing inside of him, destructive power.
The boy sometimes would yell, or sing. He talked to himself a lot. That was a way to pass the time.
He would tell stories, stories of handsome princes and beautiful princesses, of love and betrayal. He talked about Wendy, and Mabel, and Stan, and Bill. He talked about everyone he could think of, found a way to incorporate them into the story. And of course, he was the hero. The knight in shining armor to save Wendy, the damsel in distress.
They were a distraction, the stories. A way to forget that he was trapped twenty feet beneath the Earth without anyone having the slightest clue he was down here.
He would often wonder how much time had passed. Seconds, minutes, hours, days, weeks, months, years, decades? There was no way to tell, and it boggled him.
He found he could float, shortly, and in a puddle he saw his reflection. He wasn't human anymore, he realized. No, he had two arms, two legs. He had a wonderful voice, one that didn't crack anymore, but... He was an upside down blue triangle, and he had a single eye.