Captain K'nuckles is a lazy, old, liar, good-for-nothing, taking-advantage, lady-hater, do-nothing-for-everyone-but-himself, rowdy adventurer & retired bounty hunter from Poopville who seeks to become ruler of the fabled Candied Island with his cabin boy, Flapjack.
K'nuckles first appeared in the first episode Footburn & is the second main protagonist, next to Flapjack. K'nuckles always is seen around Flapjack becuase he is his best friend. In Gone Wishin', K'nuckles is revealed to be wanting to go to Candied Island & Flapjack is in to help him, along with his goal. A mermaid (which he & Flapjack accidently killed) tells him that in the future, he will become ruler of Candied Island. K'nuckles also tells Flapjack not to worry much. In Sea Legs/The Final Rise Of Cthulu, Flapjack convinces K'nuckles to use Cthulu's legs until Cthulu returns for them. K'nuckles soon takes advantage of the legs & doesn't know how to take it off when Cthulu arrives to reclaim them. Cthulu then destroys Stormalong & Flapjack makes a deal with him. If he gets his legs back, Flapjack, K'nuckles, & The Retarded Whale will move away, if K'nuckles keeps his legs, the trio will stay & Cthulu will longer have them. The legs choose Cthulu & the trio are forced to find a new home while Cthulu destroys the harbor. K'nuckles also annouced that there will be more adventures in another season.
In K'nuckles You Animal!, K'nuckles was asleep when Flapjack got taken away to an orphanage. K'nuckles wakes up & wants to tell the Retarded Whale something. After a lot of thinking & slacking off, K'nuckles is revealed to have a secret crush on the Retarded Whale & gets her pregnant. K'nuckles & The Retarded Whale then break into the orphanage to save Flapjack. Before they got arrested, Flapjack is giving the oppurtunity to stay with the duo. In Come Home Cap'n, K'nuckles is now married to the Retarded Whale, but they quickly get divorced & she kicks him out for good. Doc Boy luckily let K'nuckles live in a crate behind his restaurant. Flapjack tries to convince K'nuckles to come home, but he refuses to since the Retarded Whale won't take him back. K'nuckles later at night sings about why he needs the Retarded Whale to love him back. The next morning, Flapjack tells K'nuckles that he found a new home for him on a flyer. K'nuckles later goes inside the Retarded Whale to apologize & tells everyone to leave. After helping the duo, Flapjack asks if K'nuckles can come back live with them. K'nuckles says that only if the Retarded Whale takes him back. Flapjack says that he can't remarry her, but the Retarded Whale sort of accepts & says that she was in love with him throughout the entire show. In Rye Runt Roo, K'nuckles is revealed to have a past experience of being a bounty-hunter, but is now retired. K'nuckles later returns to his duties to kill a dog to get a lot of money, but later bonds with it & saves Flapjack from Ganon.
In On Our Way To Johto, K'nuckles finds the location of his lost anus & he & Flapjack go to Mt. Silver to retrieve it. Before reaching the summit, K'nuckles tells Flapjack another backstory of how he really lost his anus at Mt. Silver. K'nuckles & Flapjack get it back, but its unknown if K'nuckles still has it with him. In Doc Kong, K'nuckles is seen without his hat for the first time. Doc Boy (who is turned into a chimp) steals it & he & Flapjack have to get it back, which they do with the help of Gay Luigi (who had a crush on K'nuckles until the end of the episode). In The Flapjack Dub Christmas Special, K'nuckles had a horrible past of Christmas when he was a child. His dad convinced him that Santa Claus was a murderer, so he destroyed anything that ever involved Christmas. K'nuckles was hoping for a weapon on Christmas, but instead he got sacked by the Hitler Mermaids. Flapjack decides to help him become a better person before Christmas, but fails. The Hitler Mermaids return to sack K'nuckles again, but they manage to escape them when everyone ganged up on them. K'nuckles still didn't get a present because he was still bad.
In Kancelled K'nuckies, K'nuckles got kicked off the show due to cursing when an upcoming episode of Ed Edd n Eddy was about to be premiered, but got cancelled for reasons unknown. Flapjack & The Retarded Whale did everything to get him back on & it worked. In K'nuckles The Tutor, K'nuckles has a lazy contest with Ganon & beats him by default. Pretty soon, everyone gets inspired by him & wishes to learn from him (including Eddy). Flapjack pretty soon gets kidnapped & he has to fight Ganon again. K'nuckles wins again, retrieves Flapjack, & Ganon's soul leaves his 5th body. In Revenge Of The Perkins, The Sea Perkins return by taking over the Storyteller's Club (which K'nuckles used to go when he was little) & were back for revenge on K'nuckles. K'nuckles tries to bond with them to regain their respect, but instead Flapjack gets more respect when the Sea Perkins try to befriend him. During dinner time, The Sea Perkins ban K'nuckles from the Storyteller's Club due to invading their hangout & feeding them bad food. K'nuckles makes his own club, but fails so he decides to get back at them by breaking in at night. The duo find the original storytellers & tell him that the Sea Perkins kidnapped them. K'nuckles soon gets the Sea Perkins arrested & vow to get back at him one day. In the series finale The Flapjack Dub Movie, K'nuckles helps Flapjack try to get Tittering's diamonds & says when they take over Poopville, they will call it Crapville. They soon fail & get kicked out of town, they soon find an island called Pangea. K'nuckles finds a window and holds onto it, once they land on the island. Flapjack tells him that they are going to find his dad to help them get back in Poopville. Flapjack sees stuff that Poopville & Stormalong didn't have & K'nuckles explains it to him what they are because his dad told him. While in the desert, Flapjack brings a memory of when he & the Retarded Whale first met K'nuckles. They found him in the middle of the sea because he got thrown off a ship. K'nuckles gives Flapjack the window because he thinks they are going to die. After a nap, they wake up to find a group of small people known as Nomens. Flapjack tells K'nuckles that the leader is his dad. K'nuckles' dad decides to give his son & Flapjack anything they need. Flapjack tells him to rule the world (Flapjack's wish) & the location to Candied Island & succeeds. K'nuckles, Flapjack, & the Nomens encounter Ganon (for the final time) & 2 giants blocking their way home. Flapjack gives Ganon the window K'nuckles had. Ganon reveals the window to be his lost eye-lens, becomes the ruler of Pangea again, & helps K'nuckles & Flapjack back to Poopville. In the end, everyone (except for Mr. Mario, The Sea Perkins, Billy, K'nuckles' dad, Doc Boy's relatives, & Ganon) celebrates Flapjack's achievement of becoming ruler of the world at the Candy Barrell.