Vaughn on two occasions. One is when he talks to Karl and doesn't hesitate to tell him that he is very protective of Frank and Linda and wanting to know if Karl has any intention to harm them. Karl wouldn't, but it's still pretty badasss. The second time was a minor, but Vaughn shielding Frank when Doyle and Linda are fighting. Even after Frank attacks Doyle he still takes a protective stance to him like it was his own son.