May cats do things like chew on paper, boxes, wool/cotton material, etc. This is called wool sucking. If he eats it, then it is called pica.
This behavior can start because of early weaning from the mother. It cam also be from something missing in the diet. Adding fiber to his diet may be able to him stop doing it. You can add fiber by putting plain canned pumpkin in his food or metamucil fiber supplement type products.
The good news is at least paper can be broken down in the digest tract, and pass through in the stool.