Bill Cipher is a dream demon. He is also your dad. It's not easy to be his kid, since he's constantly away concurring universes, but you can manage just fine.

As a half-demon, it's hard for you to make friends. One day, you float down to earth, just yo see it... You encounter a pair of thirteen-year-old twins, Mabel and Dipper Pines

You become fast friends. Little do they know you're a demon, and little do you know, your dad is trying to take over their world