How did I get in Gravity Falls?

Amanda

------Amanda's POV------
"Now then- lets get these ropes off me." Dipper says, grinning. The ropes glow red and slowly begin to unravel. My eyes widen, we took his jewel- didn't we?! But his jewel doesn't glow red! I bang on the door once again. "Help!" I yell.

----Bill's POV----

A little flash of yellow blinds me for an instance, and I figure that Amanda must've tried to leave- but as the flashes of yellow continue, I start to get suspicious, why is she opening the door so many times? I swallow a lump in my throat. 'She'll be fine Cipher, your over reacting...'

--------Amanda's POV---------
I banged on the door for what's seemed like the 500th time.
"Anyone out there?! Please! Help!" I yell, banging on the door. The door flashed yellow every time I hit it, which means Bill knew I was doing it- so where was he? Where did they go-?!
Someone grabbed both of my arms and held them tightly and I knew who it was-
"Let go of me you creep!" I yelled. He rolled his eyes.

"Your so stubborn Demon girl, just like Pacifica..." he mumbled. Pacifi- Ohh right, different dimension... He must've been like Gideon who fell in love with Mabel, but in the end Pacifica thought he was a total psychopath... I can see why. ((This is my version of Reverse Falls btw))

"I have a name ya' know, and it's not demon girl." I growled, struggling once more to get out of his grasp.

"Ohh I know- it's just so much more fun to call you demon girl~" he cooed, shivers ran down my spine and I glared at the wall. After what seemed like only a few seconds, I heard a large 'BANG' and my head sprang up, looking down at the now unconscious Dipper Gleeful. My eyes darted up to the doorway, where a girl was now standing.

"A-Are you okay?" She asked, obviously panicked.

I nodded my head quickly too shocked to speak, "We have to get out of here before he wakes up!" I say quickly, then feel a hand grab my ankle and look down to see Dipper, I shriek and kick him as hard as I can, quickly stepping over to the large metal door.
The girl just nods and we start to run back up the stairs.

"So- uhh, My names Amanda- what's yours?" I ask, trying to distract myself from the set of footsteps closing in behind us.

"It's Tristan, Tristan Eternal" She answers. We come to a door and she pushes it open and slams it, we both stand against it to block Dipper from getting through.

"A-And how did you get down there exactly?!" I ask, ignoring the large thuds of Dipper on the other side of the door.

"Well, I heard someone screaming help and banging on a door, what would you do?" She asks.

"Good point-" I start, before the door slams open with a large red glow and a very angry looking Dipper storms through it. I look over to Tristan and think about one more question I should ask her but shake my head.

"Come on!" I yell quickly, helping her up off the floor and running out of the Mystery Shack door.

"Umm- who was that?!" Tristan asks.

"Just some phsycopath." I say, not wanting to explain. We run towards a strangely empty Gravity Falls and hide behind a stone building.

"What... Now..?" Tristan asks me, brushing some of her stringy brown hair out of her face.

"I'm... not.. sure..." I panted, looking around the corner of the building, I smile and turn back to her. "I think we lost him." Her electric blue eyes dart down to my wrist.

"Umm- what's going on with your wrist?" She asks.

I hold it up and see that the black-triangle that was imprinted on my wrist when NightShade died was still there, and now it was flashing red. ((Remember that? Yeah- it was important, very important.))

"I-umm... I don't really know-" I say, rubbing the strange mark on my wrist. She looks up into the sky, a look of terror crosses her face.

"Found you~!" A voice calls from above us, I look up to see Dipper Gleeful, who's hand is flashing red each time the mark on my wrist flashes. What on earth-
I suddenly feel a burning sensation on my wrist and I float off the ground, immediately feeling an iron grip clamp down on my wrist. I look up to see Dipper.
Not good....

I feel something hard hit my back and I turn to see Mabel and Dipper (Pines) throwing rocks at Dipper G and me, that Tristan girl is with them. 'Now I'm going to have to explain alternate dimensions to them...' I think. Dipper scowls down at them as Bill and Will appear next to Dipper (Gleeful) and he grins.
"See you later~ Demon girl." He chuckles, vanishing into nothing. Bill and Will grab my arms so I won't fall and fly down to the roof where Dipper, Mabel, and Tristan are.

"What was that?" Bill asks as we land on the roof.

"Hey- you locked the door on me!" I yell, glaring at him.

"It's not my fault he broke out!" Bill yells back.

"Please stop yelling." Will whimpers.

"No!" Bill and I yell in unison.

"Umm- guys..." Mabel starts, pointing behind us. I look in the direction she's pointing to see Tristan.

"Umm- were you- are you- what are-? Were you guys just flying?!" Tristan yells, pointing a finger I to the sky in disbelief. Bill turns back to me.

"And who is she?!!" He yells.

~~~~~~~~~~~~~~~~~~~

Alright- so Tristan is actually based off of OverlyFluffyBunny

She asked me if she could be in the book
And then I put in a lot of other people so I'm not putting in anymore characters.
(Sorry!!! :( )