"All Your Fault" is the ninth episode in the fifth season of Adventure Time. It is the one hundred and thirteenth episode overall.
A mission to help the Earls of Lemongrab lead Finn and Jake to discover grotesque new developments in the Lemon Earldom.
Princess Bubblegum is doing research when she gets a message from the Earl of Lemongrab and Lemongrab 2 saying that they're out of candy and they demand her, blaming her despite the fact she left them with enough to last a lifetime. Bubblegum sends Finn and Jake to the Lemon Kingdom with Candy seeds so the Lemongrabs can grow more candy.
As Finn and Jake arrive at the Lemon Kingdom, they are confronted by Lemon people, distorted creatures who resemble the Lemongrabs. The Lemon people, starving from lack of food, attempt to eat Finn and Jake, forcing them inside the Castle Lemongrab. Here they meet Lemonjohn, a giant Lemon person who informs them that the Lemongrabs are in the dungeon for three weeks and show them the way to it.
After traveling through the innards of the castle, they find the dungeon and discover the malnourished Lemongrabs. They find out that Princess Bubblegum accidentally left the formula of Candy life at Castle Lemongrab and they used all their candy to create their own candy people, locking themselves in the dungeon to prevent their citizens from getting any candy so they could create more citizens. Finn and Jake then gives them the Candy seeds, but instead of planting it they use the candy seeds to make another lemon person and Finn suggests they see Princess Bubblegum. They gather all the lemon people together and the Lemongrabs announce they intend to steal all the candy from the Candy Kingdom and use it to make an army that will steal all the candy from the world so they can eat it. They send Lemonjohn to carry out the task of destroying the kingdom.
As Lemonjohn was heading to the Candy Kingdom, Finn then remembers seeing the giant Lemonjohn's organs spread around the Lemon castle, Jake then said that they will never find his heart again, then Finn and Jake also remembers that there is that juice that comes out through the vent and went inside it, then attempted to stop him by smashing his exposed heart. Jake then smashed his heart, however, doing so causes his heart to start beating and gave him emotions. He realizes what he's doing is wrong and confused of what he is about to do, but then he decides to sacrifice himself for the Lemon Kingdom, dissolving himself into a mountain of lemon candy for them to eat. Later, Princess Bubblegum erases the Candy life formula from the Lemongrabs' minds and Finn said that he also took the Candy life formula form the Lemon castle, then Jake asks if he could just do the same as he did to Lemonjohn's heart so they can be more selfless and less selfish, but Princess Bubblegum remarks that there's nothing wrong their hearts, but they're always like this.
- This is the first episode that Lemongrab doesn't say "acceptable" or "unacceptable." However the word "ACCEPTABLE" can be seen written inside one of their brains during the ending close-up.
- The Lemongrabs refer Princess Bubblegum as their mother, calling her "Mother Princess."
- The way that Lemongrab and Lemongrab 2 speak (completing the sentence of each other) and walk (on a symmetric way), is a well know trace of fictional twins to act, such as Si and Am from Disney's Lady and the Tramp and I and Am, bounty hunters from the series Samurai Jack.
- The way that Lemonjohn's heart starts to pump and enlarge is similar to how the Grinch's heart in the How the Grinch Stole Christmas does.
- Princess Bubblegum, Finn, and Jake salute similar to how the United States military salutes.
- The Lemon person who screams and his skin rips off is a reference to The Thing when Peter Maloney's character begins turning into the titular monster, he screams and turns his head in a very similar way.
- When the Lemongrabs are giving a speech to the Lemon people, Lemongrab 2 seems to be missing his ribcage linings on his chest.
- When Lemonjohn carries the castle toward the Candy Kingdom, he passes through the Candy Forest even though the Candy Forest is located near the Candy Kingdom, which was still far away.