What if Stan was a little too late? (This is why all of my friends hate me now)

As the shooting star flashed across the demon's solitary eye and remained there for a split second too long, Dipper knew that that would be the last time he would see his sister. He tried to scream, but nothing came out. He merely gaped at Bill as the demon snapped his fingers and Mabel disintegrated beside him. Bill's fist clenched tighter around Dipper to make up for the now-empty space, breaking a few of Dipper's ribs in the process. "Mabel..." He managed to gasp, his vision becoming blurry with tears. Bill's laugh echoed throughout the fearamid, almost covering up the loud, grief-stricken cry of, "I'll do it!"