Welcome to the Grey Family. Sounds like Wallis has quickly become "Boss." Tell him "NO" in a firm voice. If he is good give him a treat. If bad put him back in his cage. Believe me greys' are very smart and earn quickly how to manipulate you if you let them. Tell Wallis what he has done wrong. Talk to him. Like i said, greys are quite smart.
We love to see pictures of greys. Good Luck.