When Abnormal Becomes The Norm (Bill Cipher X Dipper Pines)

Two years after the fall of Bill Cipher, Dipper and Mabel came back to Gravity Falls every summer. This time, they plan to stay permanently but when Dipper make a mistake on his second day at Gravity Falls. Let's just say this summer is not as easy as their second and third summer. (Atbash - Ceasar - A1Z26)