Sling Blade

A 1996 drama directed, written and starring Billy Bob Thornton, based on a short film called "Some Folks Call It a Sling Blade," in which he also starred.

The story's about a mentally challenged man named Karl Childers who, around the age of 12, butchered his mother and her lover with the titular sling blade, because he had always learned from his parents that having sex was wrong (a detail shown in the script and seen in the short film. He was put up in a state mental hospital in Arkansas; our observation of Karl begins 25 years later, when he's about to be released.

Tropes used in this film:

 * Adult Child: Karl, perhaps, by a combination of his mental slowness, his sheltered and backwards upbringing, and his incarceration.
 * All Love Is Unrequited: Poor Frank; Karen Cross (only shown in the extended version) just shot him right down. Gender-flipped and somewhat averted with Karl and his would-be girlfriend, Melinda: Karl: "Flowers is purty."
 * Abusive Parents: One, being Frank's adoptive father, Doyle. Also,
 * All There in the Manual: Many details about Karl's upbringing are only in Thornton's short, which only covers the initial interview.
 * Berserk Button: Don't push around Frankie's mama in front of him, if you don't want everything within his reach thrown at you. Even Linda seemed shocked by the sudden ferocity in her son.
 * Bookworm: Karl. He's got a whole bunch of books he carries with him bound by a leather strap; one The Bible, one a book on carpentry, one A Christmas Carol...
 * Captain Obvious: Frankie borrows one of Karl's books, A Christmas Carol; Karl: "That's that book on Christmas I was tellin' you about."
 * Chekhov's Gun:.
 * Chekhov's Skill: He's really good with machinery, especially.
 * Children Are Innocent: Averted with Frank. You wish it weren't that way, but Doyle has made it so.
 * Cloudcuckoolander: Karl. He likes them French-fried potaters, and the way Frank talks. Also, Morris of Doyle's band and his very weird song.
 * Comically Missing the Point: A very dark example here: Charles mistakes Karl's grunts and headshakes as amusement at his perverted stories. Fortunately, Karl.
 * Enforced Method Acting: Minor but humorous: Lucas Black didn't know Karl was going to ad-lib a certain line about potted meat, and genuinely laughed as a result; the effect was still good.
 * Face Palm: When everyone's all together for dinner, Melinda related how she heard about how Vaughan and Albert are a couple; Albert seems a bit amused, but Vaughan's quite embarrassed; fortunately, Linda suggests that Karl and Melinda go out for a walk at that moment; Irony considering she admonished Vaughan for not being too pushy when he suggested that same thing.
 * Friend to All Children: Karl, natch. Of course Frank comes to love him, and the feeling is mutual. Frank's friends also don't really seem to mind him when they.
 * He Really Can Act: Billy Bob Thornton is so known for playing Jerks and Sleazes that seeing Him as the gentle but unstable Karl is something of a shock.
 * Also, country singer Dwight Yoakam is surprisingly damn frightening as Doyle.
 * Inspirationally Disadvantaged: Very much averted. The film frequently shows how Karl not only lacks basic social skills but is almost incapable of caring for himself. He also never displays any Rain Man type abilities aside from being an excellent mechanic. Some characters, such as Vaughn, seem to view him as deep and wise, likely to lampshade this trope.
 * Jerkass: No doubt, Doyle Hargraves himself. His Crowning Moment of Jerkass mixed with (only one of) his personal Moral Event Horizons is when he.
 * Even during his Pet the Dog moment where he speaks calmly to his family and Karl, he fails to see that psychological damage is real: "I didn't hit you, did I, Karl? So no apology necessary, I guess." By the way, that's the scene where Doyle discusses moving in with Linda and Frankie for good.
 * Just Joking Justification: Seems to be a favorite of Doyle's, to try to make himself seem less of a Jerkass. It doesn't work.
 * Kick the Dog: Doyle shoves Terrence, his wheelchair-bound bandmate, against the door of his house while kicking them all out.
 * Mama Bear: Linda. Unfortunately, Doyle's sheer meanness and stubbornness prevents her protectiveness from working very well.
 * Meaningful Echo: "Karl?" All four times spoken by.
 * Moral Dissonance: Invoked for the audience, as it is for many films like this.
 * Orbital Shot: Thornton thought that a half-circle version of this would be a pretty effect, and it's a good establishment for the beginning of the 5+ minute tension building to the climax.
 * Pet the Dog: Doyle actually seems capable of a facade of sweetness from time to time. Too bad he can't hold it too long.
 * Police Are Useless: (in the extended version) Because they're Doyle's friends and are a bit lax towards him regarding drinking and driving.
 * Rant Inducing Slight: Doyle sure is a mean drunk, and he likes things quiet when he's "hurtin'". When his band talks about the technicalities of being a band a bit TOO much...
 * Shut UP Hannibal: Perhaps a more minor example, as Charles was not really a major villain, but Karl.
 * Straight Gay: Vaughan, played by the late John Ritter, who once played a man acting like he was gay. Averted with Albert Sellers, who despite having only a couple of lines, surely shows his personality.
 * Verbal Tic: Karl's guttural tone, and his use of "Mmm-hmm."
 * What the Hell Hero:
 * Wife Basher Basher: How Karl responds to Doyle who is brutalizing Linda and her son Frank.
 * Woobie Destroyer of Worlds: In a decidedly more metaphorical sense than the common usage, Karl. We do have a great deal of sympathy for him, for his naivete and his just seeming lost in the huge world (near the beginning, he even  because he has no idea how to be a free man), but he still exerts a large amount of influence on those he meets. Linda, Frank and Vaughan are changed positively for their experience with him (they get a new appreciation for people who are a little different), while , and Karl's protector instinct kicks in (for an example of this, see the CMOA above).
 * Your Cheating Heart: Apparently the reason for Karl's acts (his mom cheating on his dad, that is) which landed him in the state hospital, but as mentioned in the description, a bit more detail is given in the script and short film.
 * Straight Gay: Vaughan, played by the late John Ritter, who once played a man acting like he was gay. Averted with Albert Sellers, who despite having only a couple of lines, surely shows his personality.
 * Verbal Tic: Karl's guttural tone, and his use of "Mmm-hmm."
 * What the Hell Hero:
 * Wife Basher Basher: How Karl responds to Doyle who is brutalizing Linda and her son Frank.
 * Woobie Destroyer of Worlds: In a decidedly more metaphorical sense than the common usage, Karl. We do have a great deal of sympathy for him, for his naivete and his just seeming lost in the huge world (near the beginning, he even  because he has no idea how to be a free man), but he still exerts a large amount of influence on those he meets. Linda, Frank and Vaughan are changed positively for their experience with him (they get a new appreciation for people who are a little different), while , and Karl's protector instinct kicks in (for an example of this, see the CMOA above).
 * Your Cheating Heart: Apparently the reason for Karl's acts (his mom cheating on his dad, that is) which landed him in the state hospital, but as mentioned in the description, a bit more detail is given in the script and short film.