You were the doorman in your apartment. It was your job to determine whether it's a doppelganger or your actual neighbor. One day, while you were doing your job, a doppelganger of Francis covered in blood came in and slipped his ID and entry request through the little slip. You questioned him about the blood and he said:

Francis: This isn't blood, it's a new type of milk. Scarlet milk. He said. You then shut the window in his face, but he banged on it and begged for you to let him in.