You are a shape in the Two-Dimensional realm of shapes, no one knows of the Three-Dimensional reality, exactly one yellow triangle.

Bill Cipher, or his name Billy, has a special eye which can see past the bounds of 2D. His parents, Euclid and Scalene, also triangles, don't believe him and neither does anyone else, his parents constantly send him to therapy because of his vision.

This started when Billy was a child, despite his innocence he still saw past the 2D world

Now he's grown, he's slowly been falling apart with everyone, isolating himself. Recently he's either been there, or not. You saw him floating there once and watched him fade. What you didn't know is that Bill was clipping through the 2D and 3D dimension and sees the stars beyond the flat world.

One day while he was sitting on the floor rocking about you walk up to him, you wanted to talk to him about the 3D world, because you believed him. Only for him to get startled and for his singular eye to shake in timidness

"WH- WHAT DO YOU WANT!"