The blades were too sharp, enough to cut open a person, if nearby. If the machine was to be used, it needed both their approvals. They were partners in crime. Strangely, they usually contradicted when they had to use the machine.
That night, there was a chill in the air. Everybody could feel it. He wanted to use the machine. She was completely against it. After a big tiff, he won the argument. He switched it on.
All she could do was look at the ceiling, and see it rotate. After a few minutes, she snuggled into a blanket, hugged him tight and slept peacefully. The Fan, with sharp blades, ran in full speed that night.