Wanderlust (Bill Cipher x Reader)

You're a young, shy girl living in Gravity Falls living a pretty normal life with your extremely loving mother and father. That is... until your parents end up almost dying. You must make a deal with a certain dream demon, and in exchange for your parents' lives you have to travel with Bill to the far corners of the universe to find pieces of a device. You meet many wacky and terrifying creatures on each planet you visit, risking your life to find each piece. Was the deal really worth it? What is the device really for? Can you trust Cipher? He says he's your friend, but he IS a demon after all. Keep in mind this begins about 5-6 years before the summer with the twins, beginning when you're eleven years old. The story progresses and matures as you grow up. You eventually befriend Mabel, Dipper and the crew. The content gets more "mature" as you age.
Obviously I don't own any of these characters, that honor belongs to Alex Hirsch and Disney.
This is my first time publishing any type of writing, so //constructive// criticism would be extremely appreciated!! *~Enjoy~*