As a wild Pokémon
Few details are known about Litten's past, except that it endured hardships that have brought those who can understand Litten—such as Meowth and Olivia—to tears. Litten was rescued at some point by an aging wild Stoutland, and the two began to live together. However, the Stoutland soon became too old to search for food by itself, leaving Litten to do the gathering.
As a Litten with Stoutland
Litten first appeared in Alola to New Adventure!, relaxing on the beaches of Melemele Island before it was accidentally stepped on by Ash when he was racing with Pikachu. Litten, in anger, attacked Ash with Ember and walked off.
Litten briefly appeared in Loading the Dex! in which it approached the Pokémon School and watched Komala. Litten was later seen in First Catch in Alola, Ketchum-Style!, being fed by an Old lady in a marketplace on the beach, where it saw a wild Rowlet carrying off a wind chime.
In That's Why the Litten is a Scamp!, Litten approached Ash and Pikachu in an attempt to get something to eat. When Ash offered it a piece of the sandwich, it stole the larger portion and ran off, only to be stopped and foiled by an Alolan Persian. Annoyed by Litten's trickery, Ash promised to catch it. The next day, Ash and Pikachu saw Litten being attacked by the previous Alolan Persian and stopped it. Litten, despite being on the verge of collapse, protested against being brought to the Pokémon Center, biting and scratching Ash all the way there. After being treated, Ash brought it to Professor Kukui's house, but it managed to escape in the middle of the night. Ash, Pikachu, and Rotom followed Litten to an abandoned house, where they discovered that Litten had been gathering food for an old Stoutland. Having learned this, Ash decided to give up on capturing Litten, leaving it to care for its caretaker. Suddenly, the group was attacked by the Alolan Persian from earlier. Ash had everyone leave the house, where Pikachu and Litten then started battling the Persian. Litten eventually defeated Persian, and successfully protected Stoutland. The next day, Ash discovered that Litten and Stoutland had relocated. After being assured by the old lady of the marketplace that Litten was doing fine, Litten appeared from behind her to grab the fruit she had prepared and ran off into the distance.
Litten reappeared in They Might Not Be Giants! when Ash's Rowlet and Lana's Popplio got separated from their Trainers and fought Meowth off when he tried to catch them. It took them to Stoutland, who told Litten to go and help Rowlet and Popplio get back to their Trainers. During their search, the trio got caught by Team Rocket. However, they managed to escape thanks to Litten and blasted Team Rocket off with their combined attacks. After Rowlet and Popplio were reunited with their Trainers, Litten ran off again.
In One Journey Ends, Another Begins..., Litten stole a doughnut Ash dropped and was chased back to its home by him. Ash witnessed how Stoutland helped it learn Fire Fang, but Litten was unsuccessful to master the move. Later on, Litten ran up to Ash, desperate for help with a collapsed Stoutland. After escaping Team Rocket, Ash was brought to its home and carried Stoutland to the Pokémon Center. Litten ran into the emergency room to be its friend while Nurse Joy informed Ash of Stoutland's condition. When Ash returned to the center the next day to check on Litten and Stoutland, he was shocked to see they had left. At its home, Litten practiced its Fire Fang again, but failed once more. Displeased with having the same results as its previous attempt, Litten curled up into Stoutland and fell asleep, proceeding to have a dream where it chased after Stoutland and was unable to catch up. Litten soon woke up alone and immediately flew into panic again, searching over various parts of Melemele Island for Stoutland.
Upon returning home, one of the supports of the sofa the two Pokémon had been sleeping on broke as a tree shed its last leaf and a massive storm whipped up over Melemele. Wracked with grief, Litten looked up to the sky and started yowling. Ash and his Pokémon later found Litten asleep on the sofa, curled up next to the tree's leaf, and kept visiting it to comfort the Fire Cat Pokémon. While the others were still sleeping next to the sofa, Litten woke up as the rain stopped saw a cloud formation shaped like Stoutland behind a rainbow, seemingly smiling in approval. Gathered with resolve, Litten offered Ash a Sitrus Berry. Afterwards, Litten agreed to battle Ash and Pikachu, and was able to successfully execute Fire Fang. After the battle, Litten allowed Ash to catch it, the Trainer having finally gained its trust. When sent out again, Litten happily joined in with the rest of Ash's Pokémon when he poured out the rest of the berries in his shopping bag.
In A Shivering Shovel Search!, Litten was seen training with Kiawe's Turtonator to master Fire Fang, but was still unsuccessful to master the move. Later, when Ash was stuck inside of an enraged Palossand's body, Litten got caught in its body as well when protecting Rockruff. Palossand then began absorbing Litten's life force, causing it to be unable to leave Palossand's body. Thanks to everyone's combined effort, Snowy was able to freeze Palossand with Powder Snow, stopping it from absorbing life force. Litten then managed to master Fire Fang and used it to break free from Palossand's body. Afterwards, Litten and Ash returned Palossand's lost shovel, calming the Sand Castle Pokémon down.
In Alolan Open House!, Delia visited her son and took a liking to Litten and gave it the nickname Litty (Japanese: ニャビーちゃん Nyabby-chan). At first, her sudden approach made Litten freak out, but once she started petting it, Litten got more comfortable. Delia later used Litten in a battle against Tupp, Zipp, and Rapp of Team Skull, who were attacking the Pokémon School.
In Currying Favor and Flavor!, Litten assisted Ash in clearing the trial in Lush Jungle, where it battled a Totem Lurantis. It initially had the upper hand, until Lurantis called its ally Castform, who created harsh sunlight using Sunny Day. As Litten struggled with Lurantis's now immediate Solar Blades and Castfrom's Water Guns, Ash sent out Rowlet to assist it. With the help of Rowlet, Litten was able to fight on equal ground against its opponents. After a hard fought battle, Rowlet managed to defeat Castform, allowing Litten to use Breakneck Blitz to knock Lurantis out as well. Having cleared the trial, Ash was rewarded a Grassium Z.
In SM063, while Ash was watching a Battle Royal on TV, Litten became agitated when it saw the Masked Royal's Incineroar. When Ash and his classmates later went to visit the Battle Royal Dome during a special event where anyone could volunteer to face the Masked Royal in a Battle Royal, Litten jumped down from the stands to the arena, prompting Ash to take part in the Battle Royal, joined by Kiawe and Sophocles. Although Kiawe's Marowak and Sophocles's Charjabug were soon defeated by Incineroar's Darkest Lariat, Litten managed to survive the attack. However, Litten's counterattack with Fire Fang was stopped cold by Incineroar, who then proceeded to defeat Litten with a Bulk Up-enhanced Throat Chop. This defeat later inspired Ash to teach Litten Flame Charge. Some days later, in the middle of Litten's training, the Masked Royal showed up and challenged Ash to a one-on-one battle. Litten, still not having completely mastered Flame Charge, was struggling throughout the battle. However, thanks to Ash's determination, Litten was able to evolve into a Torracat, perfecting Flame Charge in the process. Although the evolution and the Speed increase from Flame Charge gave Torracat more edge in the battle, to the point where it even managed to damage Incineroar a bit, it was still eventually defeated by its evolved form. Afterwards, the Masked Royal declared that he and Incineroar were now Torracat's rivals.
Showing off its fiery disposition as a Litten
Before being caught by Ash, Litten was a stubborn Pokémon that tended to keep its emotions and motives hidden. Its closest friend was an old Stoutland that once helped it when it had lost consciousness. Litten was seen training itself with Stoutland's guidance, and protected and cared for Stoutland in its ailing state. Litten had a very close relationship with Stoutland, and deeply cared for it, as evidenced by Litten's dreams about it. Litten had difficulty getting close to humans, but seemed to get along well with the Old lady of the marketplace. When Litten was wild, it would often visit her when it needed food.
Its first encounter with Ash did not go over so well. When he accidentally stepped on Litten's tail while running along the beach, it responded by burning his face with Ember. Encounters with Litten after that were unpleasant for Ash as well, as Litten had a tendency to attack him or steal his food, showing off cunning and slick characteristics to its enigmatic personality. When Stoutland thought it would be a good idea for Litten to join Ash, Litten wasn't keen on the idea. When Stoutland collapsed due to ill health, Litten's demeanor toward Ash began to change, and it was desperate for him to help it. After Litten accepted Stoutland's absence, it began trying to offer its food to Ash like it had done with Stoutland. Despite their growing relationship and mutual trust, Litten still shows a tendency to burn Ash in the face even after befriending him; though now it seems to be done mostly as a sign of affection toward him, much like Charizard before it.
Since its capture, it has shown to be reflecting its solicitous nature over Stoutland on its new teammates. This was showcased in A Shivering Shovel Search!, when it protected Rockruff from being eaten by an angry Palossand and has even shown to be fine with Rockruff sleeping next to itself, despite putting the fact that it did not want to play with it earlier. This shows Litten is willing to open up to its new family despite its innately frisky nature. Litten is cold and apathetic towards strangers, as shown in Alolan Open House! when it was introduced to its Trainer's mother, but can't resist being stroked gently under its chin.
Since its capture, Litten has grown close to its Trainer and helps fellow Pokémon as shown in The Ol' Raise and Switch!, where it helped Snowy warm up towards Ash and even offered Snowy a Sitrus Berry. Despite growing to care for others more, it is still shown to become a bit aggressive, as shown in Pulling Out the Pokémon Base Pepper!, where it got angry towards a nearby baseball and in Now You See Them, Now You Don't!, where it got annoyed at Ash's Lycanroc. In Night of a Thousand Poses! and Mission: Total Recall!, it is shown that Litten will spar with Lycanroc on occasion, even when it is separated from its Trainer.
Litten is also shown to have a strong sense of smell. In SM063, after sniffing the Masked Royal, it immediately recognized him as Professor Kukui.