KARL: Never did know too much of nobody down there, not to be helping me out no way, mmhmm.
The more we learn about Karl's family, the more we realize that the "nobody" he's talking about from his hometown doesn't only include the townsfolk—it also includes his family. To say he wasn't close to his family would be an understatement.
LINDA: Frank loves company. You know, especially after his daddy passed and all.
Frank, like Karl, isn't close to his father. But in Frank's case, it's because his father committed suicide. In a way, both Karl and Frank deal with thoughts that their own fathers never wanted them.
LINDA: You know he's always after a father figure. […] I don't think he sees you as a "guy" guy.
Linda's comment here sets up Karl as a father figure for Frank. Is Karl a father figure, a brother, a friend, or all three to young Frank? Why? Do Frank and Karl see the dynamic in different ways?
DOYLE: Let's all just be a family till your mentally retarded friend and your homosexual friend get here.
Doyle is the father no one asked for and no one wants. Karl, Frank, and Vaughan all wish they had better (or simply alive) fathers, but none of them are desperate enough to accept Doyle as a father figure.
VAUGHAN: Linda and Frank are very important to me. They're like family. My own family was never like a family.
We can't think of a character in this movie who doesn't have family issues. Now we can add Vaughan to the mix, with Frank, Karl, and Linda. Vaughan says out loud what Frank and Karl are doing—they are making their own family.
VAUGHAN: They're horrible people. As a matter of fact, for years I prayed every night that my father would die... and finally I realized, through a lot of therapy, that I was wasting my energy on hating him. So now I just don't care.
Lots of father issues in this movie, folks. Frank's dad is dead, and he's sad about it. Vaughan and Karl both wish their own fathers were dead. Later in the film, Karl's attitude toward his father will mimic Vaughan's—he'll stop wanting to kill his father and will instead just accept the fact that he'll be dead soon.
FRANK: That don't seem right. It seems like you would have took kept him and took care of him if he was your brother.
Frank and Karl share a sad moment when Karl admits that his younger brother was born premature, so Karl buried him in a shoebox in the yard. Frank, who would do anything to have more male family members, believes he would have made a different decision from the one Karl did, but Karl knows that his poor brother wouldn't have stood a chance.
DAD: I ain't got no boy. […] You ain't no kin to me.
We doubt Dad's opinion that he doesn't have a son, spoken to his son standing in front of him, is a new one. We imagine that Dad voiced this opinion even when Karl was young, and that played a big part in Karl wanting his own father dead.
DOYLE: See, your mama and I don't have no problems except for you. Fact is, we never have a bad word between us. But since you do exist and I'm gonna be the head of the household then you're gonna learn to live by my rules. And the first rule is: You don't speak unless you're spoken to. You got me? Now you stay the hell out of my way. And do what a regular kid does. You're a weird little s***, Frank. And I don't get you. So wake up and face what they call reality. See, we're gonna be a family, Frank. My family. I'll be paying all the bills. So that means, you're stuck with my ass, but I ain't your daddy. You just act like I am.
Doyle's idea of family sounds more like a dictatorship to us. Just sayin'.
KARL: Mmm. You're a good mama to that boy. You care for him. You work hard to care for him. You light him up in his eyes. I've seen it. That boy wouldn't know what to do without you.
We're not sure we'd go far enough to call Linda a good mama, because she does bring Doyle back into her house, knowing full well how dangerous and hateful he is toward her son. But the rest is true—although it might be true only because Linda is the only living family member Frank has left.
FRANK: I wish me and you and Mama would just run away.
By the end of the movie, Frank thinks the three of them could go anywhere and be okay. That means he considers Karl a member of the family.