It's Bill Cipher [BillDip AU]
His name is Bill Cipher; at least that's what everyone thinks. When Bill enters Pioneer High School, no one is sure what to think of him. He was sarcastic, rude, annoying, and a singer. He is Bill Cipher.
Dipper Pines hated him, he was also very aware Bill Cipher had a secret. Something that not even the administrators knew and Dipper was going to find out. He was going to get into Bill's head and befriend him- no matter how irritating he was.
His name is Bill Cipher and Dipper would learn his secret.