Carl is one of two characters in the FilmCow video, "Llamas With Hats". In retrospective, Carl may appear to be the series' antagonist, due to all the crimes he commits, but he may also be considered to be the protagonist due to be the primary character of the series.
When we first see Carl, we see him in his home with his male roommate, Paul, (though Paul's name is not revealed until the third episode), where he appears next to a dead body with multiple chest wounds and no hands.
When asked what the dead body is doing here, he responds, "I was in my room, reading a book, and uh, well, this guy walked in, so I went up to him, and I...I stabbed him 37 times in the chest."
Thus, begins his history of violence and mental health issues, which are further demonstrated on his later adventures with Paul. It is also revealed that Carl cut off the man's hands, prior to his demise, cooked the hands, and later, enjoyed them as a delicious snack because apparently his stomach was "making to rumblies that only hands could satisfy".
In the second episode of "Llamas with Hats", we see Carl with Paul on a safety raft, in the middle of the ocean, with a sinking cruise ship behind him. It is later revealed that Carl did indeed sink the cruise ship. He also murdered the captain, butted small children off the side of the ship, made out with the ice sculptures, and murdered the lovely elderly couple from 2B. He also sunk the other life boats, so that remaining victims of the boat attack could not survive.
Later, on Carl and Paul's next adventure, we see him on vacation, but with a burning civilization behind him. It becomes quickly apparent that Carl toppled a South American government, which is evidently burning behind him. He claims that it was a resistance, but Paul reveals that Carl pushed the resistance leader into a giant fan. The resistance leader was apparently trying to stop Carl from pushing other people into the giant fan. Carl also swollowed the bartender from his hotel whole, and filled his luggage with "Orphan Meat," which he was evidently collecting to build a "Meat Dragon," and not just ordinary meat would do.
In Carl and Paul's next adventure, we see them again in their home, and there is a trail of muddy hoof prints leading right up to Carl. As Paul is arguing with Carl, and Carl is insisting that the culprit of the the muddy tracks is not him, the entire back wall of the home explodes, revealing an entire city on fire, and a nuclear bomb in the center of it, to which Carl responds, "Happy Birthday!"
Later, balloons with raw faces attached to them appear in the scene, which were apparently Carl's attempt at birthday decorations. At the end of the epsiode, it is revealed that Carl is a sociopath with a long history of violence. Apparently Paul was previously aware of Carl's condition, but forgot.
But after the events of Episode 4, Carl's actions haven't surprised Paul anymore. However, Paul seems to have become paranoid, and always suspects the worst of Carl. After listing a bunch of seemingly harmless things he did during the day (including washing the car and baking a loaf of banana bread for their next-door neighbor), it is revealed that Carl created a crack in spacetime to collect millions of baby hands, which even Carl considered as totally fudged. Paul, however, does not seem impressed, thinking of it as anticlimactic by comparison to Carl's previous escapade with the nuke and the burning faces.
After building meat conveyor and naming himself "Henry Ford of human meat" he finally succeeded in processing orphan meat and building his ultimate creation, The Meat Dragon. It is also is this episode that Paul reveals he is moving out.
Because Paul has moved out, Carl has instead gotten a sheep to wear a mask of Paul's face, and Carl explains that he has made a giant hand by sewing the faces of members of the City Council together. He claims that he disagreed with the election results, and calls himself a patriot and a hero.
He then becomes annoyed when the sheep playing Paul decides to sit down, mentioning that Paul never sits down and is always standing.
Carl visits Paul's new home with the hopes of reconciling, only to reveal that because of the mask of Paul's face that Carl has been using, Paul is now a wanted criminal, believed by authorities to be in charge of a Russian opium cartel. It is also revealed that Carl has burned down his house after it was filled with swans, and he is broke because he spent all his savings on the swans.
A "swan piano" then crashes into Paul's house, which Carl made with the intent to send to Paul as an apology gift, but his plan backfires and Paul just becomes angry.
Carl hangs the mask of Paul against a tree, and starts imitating a conversation that he and Paul would probably be having. Pieces of blood and flesh are scattered across the floor, but what happened is never actually confirmed.
Then, someone says the name "Carl", but it wasn't Carl himself. The eyes of the Paul mask start to glow red, and it levitates away from the tree and starts talking to Carl, telling him that he has to finish his work.
Carl wakes up submerged in darkness, and when the Paul mask turns on the light, he realizes he has fallen into his Gore Pit. He suspects that his legs are broken, and a bone is sticking out of his right leg.
The Paul mask warns him on incoming danger, and Carl reassures him that the basilisk he keeps in the Gore Pit doesn't eat people. The mask then goes in search of rope to help Carl climb out of the pit, but is unsuccessful, and Carl is left to his own devices.
Carl has seemed to wipe out civilization, but the Paul mask keeps calling out Carl's name in an irritated tone, and saying that he still needs to "complete his work". Carl begins to doubt that the mask is actually Paul, and says that he is going to go and find the real Paul.