Braixen, as a Fennekin, is a very friendly and kindhearted Pokémon with a very bold heart. She tends to mimic Serena as shown when she stretched like her. Like her trainer, she detests getting dirty, and always takes great care to look her best at all times, and can get angry if she gets dirty. However, she overcomes her fear of untidiness and learns an important lesson in doing so in order to protect Serena, though she never loses her desire to be beautiful. Fennekin can sometimes be very temperamental with other trainers and their Pokémon but she always obeys Serena, and is quite affectionate towards her. Fennekin also shows her love of twigs when Serena feeds it to her and the twig she eats is similar to a pocky stick.
After evolving, Braixen is shown to be the same as she was back as Fennekin. However, she is very attached to her branch especially when its old branch broke and was very picky when her friends tried to find a replacement.
Braixen took a liking to Serena the minute she was chosen to be her partner when she was a Fennekin. Also, Braixen and Serena are very close as they enjoy doing various things together. Braixen and Serena don't hardly butt heads with each other as they usually get along with one another.
Fennekin first appeared as one of the three starter Pokémon new trainers can choose from Professor Sycamore, and was chosen by Serena as her starter Pokémon. As Serena and Fennekin travel through a forest, Serena mistakens a wild Vespiquen as a person, who later attacks them. Fennekin protected her trainer by scaring Vespiquen away with an Ember attack. Fennekin was later sent out to introduce herself to Ash, Clemont, and Bonnie.
Fennekin was seen eating lunch along with the rest of the Pokémon while being watched by Team Rocket at their Meowth Balloon and watching Ash cleans up one of the wild Pancham in the face. She along with Chespin, Pikachu and Froakie are caught by them. However, when both James' Inkay attacks Jessie's Wobbuffet with Psybeam due to their arguments, Wobbuffet deflects the attack using Counter as it destroys their balloon. Fennekin was later separated with Pikachu, Froakie and Chespin as she tries to make a tidy on her tail by licking it until they found her. She also became suspicious about Meowth when he's around with them. But she was still upset because her tail is untidy as Froakie uses its frubbles to clean it up as she thanked Froakie for cleaning it as Froakie blushes in front of her. As Pikachu picking up Dedenne's electricity, Fennekin is seen eating a twig much to their surprise as Chespin tries eating it the same but it was disgusting as he threw on a wild Pangoro's forehead causing it to get on the rampage as everyone makes a get away as Chespin hits it with Pin Missile in fear as Pangoro's bamboo's sprigg is burned and does not move without it to the surprise of both of the wild Pancham as they are reunited with Ash and the group. Fennekin is shown being carried by Serena and later following the wild Pancham to get a special bamboo sprigg. After Chespin gets the sprigg, they were confronted by Team Rocket as Jessie shows her new Pokémon, Pumpkaboo who uses Leech Seed on everyone to sap their energy. Ash quickly rushed to put Pangoro's mouth with its bamboo sprigg as Pikachu repels Inkay's Psybeam with Thunderbolt while both Froakie and Bunnelby also repel Pumpkaboo's Shadow Ball with their powerful abilities and Fennekin and Chespin knocks Wobbuffet with the combination of Flamethrower and Pin Missile before it could use Counter as Ash successfully put the sprigg on Pangoro's mouth causes it to release itself from the bound and blasts Team Rocket by knocking them to the sky using its Mach Punch as Fennekin and the others are free from its Leech Seed. The wild Pangoro finally accepts their apology for causing a lot of trouble, it allows the two Pancham to play with them before they parted ways in a sunset. 
Serena finally shows her Fennekin to the kindergarten students as she describes her personality. 
Fennekin is later seen eating with the rest of the Pokémon during camping at night and became shocked to see Chespin ate most of the macarons. 
Fennekin was seen being carried by Serena throughout Ash's journey and later being treated and the other Pokémon at the Pokémon Center. 
Fennekin later helped Serena prepare a video performance called PokéVision. But during the filming, Fennekin was taken away by Team Rocket and her trainer and her friends went off to find and save her. When they found her along with Pikachu and Dedenne, Fennekin was hesitant to walk across the mud puddle because of her fear of being untidy. However, when she saw how Serena bravely risking her life to save her, she found the courage to run across the puddle to reach her trainer. In the battle against Team Rocket, she learned Flamethrower and sent them blasting off. After Team Rocket blasted off, Fennekin and Serena managed to finish the video and broadcast it just in time.
Fennekin was later released by Serena when she had caught a wild Corsola during fishing. Unfortunately for Fennekin, she is afraid of getting washed up from its Water Gun as Corsola directly hits Serena on the face as it gets away. Both Ash and Clemont scold Fennekin to fight it rather than running away as Fennekin becomes picky on both of them which Serena tells her that she can fight the next time they encounter another Pokémon which she agreed. 
Fennekin was released by Serena to deal against Meowth using Hidden Power but Meowth disperses the attack using Fury Swipes until Aurorus freezes him with Blizzard while Alexa tries to release Amaura from their truck. 
Fennekin was initially seen with other Pokémon during their lunch break before Serena decides to take fishing. 
Later, Fennekin and Serena both participated in the Poké Puff Contest and were competing against Miette and her Slurpuff. But the contest was interrupted when Team Rocket stole the ingredients. Serena, Fennekin and their friends went off to look for the ingredients until they were ambushed by a group of angry Swirlix. Fennekin tried to protect Serena ended up getting entangled in Swirlix's sticky thread, but was eventually rescued by Ash and his Pikachu. She then scared the Swirlix away with a Flamethrower. When the gang were fighting against Team Rocket, she combined her attacks with Slurpuff and Pikachu and sent them flying. With the ingredients retrieved and returned, she helped Serena in the final round of the contest, but lost against the Berrybaker kids. Fennekin teams up with Ash's Froakie and Clemont's Chespin to fight off Team Rocket after they captured Pikachu. They tried to fight both James' Inkay and both Jessie's Pumpkaboo and Wobbuffet. Fennekin was bumped into Froakie when Wobbuffet uses Counter to deflect back his Water Pulse especially Chespin's Pin Missile. They tried to dodge most of their attacks until Gray's Flabébé assists them to put Team Rocket and their Pokémon to relax and comfortable using Aromatherapy as the trio watches them being affected before Ash and the others recalled them and returning back to the hospital to see Gray and his wife to see Flabébé regains its Fairy Flower. 
Serena later released Fennekin as her partner while they are making flower arrangements with Ash and the others and this is the training for Korrina in how to make her and Lucario's hearts are one when it was mega evolved. 
Serena releases Fennekin to fight Team Rocket off in mid-air and destroying the Meowth Balloon using Flamethrower to make a crash landing. Fennekin was seen hanging on Serena's shoulder as she watches Ash's Fletchling beats all of Team Rocket's Pokémon and to cut off the net using Steel Wing to rescue Moria's Talonflame as she allows her Talonflame to blasts Team Rocket off with Fire Blast.
Later, Fennekin was seen with Ash's Pikachu, both Clemont's Chespin and Dedenne and Bonnie to cheer Fletchling to do battle with Moria's Talonflame. She also jumps in excitement with the rest when Fletchling finally evolves into a Fletchinder when Talonflame directly hits it uses Fire Blast leading it to defeat Talonflame with its newly learned Flame Charge. She and the others also congratulates Ash and his Fletchinder for their win. 
Fennekin was along with Pikachu and the others to have a Poké Puff break when Ash tries to train both Froakie and Hawlucha on working together in a double battle until Chespin ate most of the puffs knowingly that he ate one of the puffs are from Fire-types. Serena angrily scolds it as Fennekin, Bunnelby and Pikachu became angry for its gluttonous behavior. When Ash was kidnapped by a wild Trevenant, she along the rest of the Pokémon and their Trainers are trying to search for him until Serena and Clemont recalled their Pokémon back. 
She was later used in Pokémon battle against Serena's rival Shauna and her Bulbasaur. Fennekin launched a strong Flamethrower but was countered with a close range Energy Ball. Astounded with Bulbasaur's power despite its type disadvantage, Serena and Fennekin lost the battle due to the First-Touch rule.
Fennekin was seen with Ash's Pikachu and Froakie and Clemont's Chespin as they follow Serena on the lead where they a take a hundred meter dash. When Professor Sycamore makes an activity for all the group to make a PokéVision involving on making Poké Puffs, Serena decides to make those as Ash and the others will do the same. Later, Fennekin was released by Serena as she feeds it with a twig. She watches Serena treats Ash's swollen right foot after he and Serena slipped down into the edge of the cliff especially when Serena decides to find her own dream with her Pokémon as she is carried by her. Both are soon rescued by Professor Sycamore and three rescuers which is Jessie, James and Meowth in disguise. Therefore, Fennekin was excited with the other Pokémon play in a grass full of flowers and it was a perfect time for them to make their PokéVision. Fennekin is last seen along with Froakie, Dedenne, Pikachu and Chespin in Serena's own PokéVision when they chased the rolling Poké Puff as Chespin ate it much to their disappointment. When Serena had more Poké Puffs, everyone tries to grab it but they soon scrapped the whole thing. As Serena's PokéVision later reveals as one of the three's best PokéVision, Shauna congratulates them. 
Fennekin was seen with Ash and the group when Professor Sycamore gives them another activity during camp was Pokémon Orienteering. As the activity finally begins, they tried to find every checkpoint to get some stamp until Bonnie loses her way along with Pikachu and Dedenne in a forest covered in a fog. Fennekin is always with Serena with Ash and the group when they go separately with Shauna's group to find Bonnie until they find Ash's Pikachu who is asleep due to the effects of a wild Amoongus' Sleep Powder after the fog clears until they find Bonnie at the other side of the cliff. After rescuing Bonnie and risking their lives to get her back with the help of a wild Drifloom, both teams ended up lost in the Pokémon Orienteering as the points gives them from the other groups. 
Later, Fennekin watched a Pokémon Showcase with Serena, Shauna, and Bulbasaur and got to see Aria, the Kalos Queen, and her Braixen in person for the first time. They were incredibly amazed at Aria's performance and it inspired Fennekin and Serena to compete in Pokémon Showcases. But when another trainer named Kayleigh and her Furfrou went to have a turn to perform, a wild Pancham suddenly appeared dancing on the stage and interrupted the show. Fennekin later tracked down Pancham and learned that Pancham has a dream of becoming a great performer. Fennekin decided to help Serena catch it, but during the battle, she ended up getting caught by Team Rocket. But after the brave heroics of Fletchinder, Chespin, Pikachu, Dedenne, and Pancham, Team Rocket was sent blasting off. Fennekin and Pancham resumed the battle, and Fennekin managed to defeat Pancham with Flamethrower and Hidden Power, thus allowing Serena to successfully catch Pancham.
Fennekin and Pancham were sent out to perform a demonstration to a performer named Nini. During the demonstration, Fennekin and Pancham used their powers to create a firestorm. After that, Fennekin and Pancham were captured along with Clemont's Chespin, Nini's Farfetch'd, and Nini's Smoochum. Fennekin was a bit annoyed and Pancham and Chespin's constant fighting during her escape from Team Rocket, but when she tried to fight against Jessie's Pumpkaboo, she was immediately defeated. However, Pancham and Chespin worked together to save Fennekin and sent Team Rocket flying. Afterwards, Fennekin was reunited with her trainer.
Fennekin participated alongside Serena in the Coumarine Rookie Class Showcase. Unfortunately, during the first round performance, Fennekin tripped over a bow from her outfit Serena decorated for her. This eliminated them from the showcase, leaving Fennekin saddened and mortified, but Serena calmly reassured her. When Serena began to cry the following morning, Fennekin tearfully tried to lift her trainer's spirits, ultimately forcing her into a hug alongside Pancham. She and Pancham watched as Serena cut her hair and cheerfully presented her new appearance to Ash, Pikachu, Clemont, and Bonnie later on.
It later used its Scratch attack to free Dedenne from a Pokémon Hunter's cage. Later in the same episode, Serena and Fennekin battled alongside Ash, Pikachu and Team Rocket and their Pokémon against the Pokémon Hunter and his Rhyperior, contributing her Flamethrower attack to form a maelstrom of energy to knock out the perpetrators.
After watching a video of Shauna's performance in the Coumarine City Showcase, Serena was determined to train more with both Fennekin and Pancham. Their practice was riddled with difficulty however when at first Fennekin accidentally burned Pancham and again when the latter accidentally slips on the former. When things started heating up between the two, Serena tried to intervene as Pancham antagonized Fennekin from its position on her shoulders. Fennekin had enough and used Flamethrower, aiming for Pancham but ending up burning Serena instead making Serena angrily yells from their actions but eventually runs away, crying in shame. After Serena lost her temper, snapped at them and left in a state of shame for doing so, Fennekin stood with Pancham by the window worrying about her as Ash attempted to relieve their concerns. When Serena returned to apologize to her Pokémon after she hangs out with a disguised Aria, Fennekin happily jumped into her arms to welcome her back. Later, during Serena's double battle against a disguised Aria, Fennekin started out with Scratch only to be deflected by Aria's Aromatisse. When the chips started looking down, Pancham protected Fennekin from an oncoming Flamethrower from Aria's Delphox Serena remembered something Aria had told her earlier and assured her Pokémon things would be fine. As she and Pancham work together, Pancham unleashes its Stone Edge to make Fennekin step up and fires her Flamethrower while Delphox deflects the same attack and it was strong enough to knock Fennekin out. As Pancham defends Fennekin with Aromatisse's Charge Beam while holding off using its Dark Pulse, Serena finally gives her Pokémon some confidence not to give up and Fennekin hears her words.
Desperate to stand up and fight, she evolved into Braixen much to Serena's surprise and both Ash and Bonnie's excitement as she remembers the time with Serena together as a Fennekin during her evolution. Pancham was happy to see her evolve as he manages to disperse Aromatisse's Charge Beam with his Dark Pulse onto the sky and bursts in a double colored sparkle. Their fight briefly resumes when Pancham's Dark Pulse hit them both as a distraction until Braixen's Flamethrower deals serious damage to Aria's Pokémon in a burst of fireworks. The battle is interrupted when Aria's phone rings knowing of her works as she postponed their battle and she immediately parted ways with Ash and the group, promises to meet Serena again. After Aria had to leave following an abrupt phone call, Serena hugged her Pokémon, and their quarrel is all over.
Braixen was seen along with Clemont, Bunnelby and Pikachu after being separated by the three Pangoro until being reunited with Serena along with Ash, Frogadier, Hawlucha, Chespin, Fletchinder, Clemont's Luxray. 
Later, Braixen was watching the fashion art with her trainer and Bonnie and joined them in fashion show. She later watched a video and learned with Serena and Pancham about the next performance and it's next location.
Braixen got prepared for the next performance. Despite Serena's dress getting torn by Jessie who disguises as Jessilie and gotten shorten to get fix, they managed to pull through and pulled off a great performance, allowing Serena to win.
Braixen was used to fight Team Rocket's Pokémon as her Flamethrower along with Pikachu's Thunderbolt is used to blasts them off. 
Braixen also helps Pikachu and Chespin to cool off the wild Snover's fever using snowballs to melt the fever down before Clemont makes a medicine for it. When Team Rocket captures the wild Abomasnow for attacking them on purpose, Braixen was lifted up by Clemont's Chespin's Vine Whip so that she releases Abomasnow by cutting the net using Scratch. 
Braixen teams up with Pancham, Serena and Bonnie to volunteer to help Nurse Joy by giving berries to other trainers to heal their Pokemon. 
While Serena and her Pokémon perform for their next performance, Braixen's branch gets broken after Pancham accidentally hits her from behind using Stone Edge, which makes her devastated as she screams. Braixen ends up getting upset over her broken branch. The other tried to get a new branch for her, but she turned them down, as she would never replace her branch. They visit a woods carer named Woodward, hoping he would help with something with the broken branch. Whilst battling to figure out what to do, Team Rocket attacks despite James is trying to help Serena from earlier. Braixen and Pancham do a performance attack where she connects her broken branch and learned Fire Blast to blasts Team Rocket off, but in the process, her branch gets broken into more pieces. Pancham soon gives Braixen a new branch and she accepts it. Serena then puts a red bow on it as an addition to remember her old branch. The gang then ties her branch pieces to lay them to rest just as the gang left for their next destination.
Braixen was seen with Serena and Pancham saw a wild Eevee who gracefully dances in a stone similar to a dancing stage. She along with Serena and Pancham do the Pokémon performance so that Eevee could watch them. Altogether, Braixen teams up with Pancham to fight Team Rocket's Pokemon after they captured Eevee until she blasts them off with Swift. Braixen was seen with all of the group's Pokémon to introduce Eevee who is later revealed to be very shy to humans and fellow Pokemon alike as she hides behind Clemont's Bunnelby's back.
Braixen was seen with Chespin, Pancham and Ash's Frogadier watch the tag battle between Ash's Pikachu and Tierno's Blastoise against Serena's Eevee and Shauna's Ivysaur until Serena calls off the battle due to Eevee's graceful dance move is used to beat Blastoise own hip hop dance moves to hit it with Swift. 
After Serena won the Theme Performance of the Anistar Rookie Class Showcase, Braixen along with the others searched for Eevee, who ran away in fright due to her fear of fireworks coming from Jessie's performance in the Pokémon Showcase as Jessilie and her Gourgeist. After successfully finding the missing Eevee, Braixen performed along with Serena and Pancham in the Freestyle Performance. Serena and her Pokémon danced, inspired by Eevee, before Braixen finished their performance by launching a Fire Blast in the air. Having dazzled the audience with their moves, they received the most votes, successfully earning Serena her second Princess Key.
Braixen was later sent out to help along with Ash's Frogadier, Pikachu, Clemont's Luxray and Sawyer's Grovyle fight off Celosia and several Team Flare Grunts to protect a strange Pokémon called Squishy before Serena recalls Braixen back.
Braixen was with all of Ash and the group's Pokémon are watching shooting stars at night and later searching for Squishy until Clemont's alarm had exploded. 
Braixen was used in the Couriway Rookie Class Showcase along with Eevee, this time in the performance. During the night, she comforted Eevee along with the others to build up her confidence. Braixen and Eevee stayed behind in the waiting room for the Theme Performance while Serena and Pancham entered, then lept for joy over their victory, which made them qualify for the Freestyle Performance. She performed well along with Serena and Eevee for the first part until Eevee had fallen, shocking her. After Eevee had gotten encouragement from Serena, Braixen continued the performance and finally ended it with Fire Blast once again. Although they had lost, she had no hard feelings over it.
While traveling to the Terminus Cave, Braixen used the flame on her stick as a torch to help find a way through the dark. However, the group was suddenly attacked by Team Flare and Braixen helped fight the villainous team. But the battle was stopped when Squishy changed into its 10% form and defeated Team Flare and their Pokémon. She and the others also defend Ash's Greninja before he transforms into his special form to face Celosia's Manectric and Bryony's Liepard. Afterwards, she along with the other Pokémon try to cheer Bonnie up before they continue looking for Squishy as the former remain in hiding while in its invisible state. 
Braixen alongside Ash's Pikachu to rescue Bonnie from several wild Scolipede using both Flamethrower and Electro Ball. When Pikachu was captured by Team Rocket, Braixen teams up with Ash's Greninja to rescue it by destroying the Meowth Balloon using Flamethrower and Water Shuriken combination forcing James and Jessie to release both Inkay and Gourgeist to face them as the battle goes in 2 on 3 handicap. As she, Greninja and Pikachu dodge their attacks and using Scratch and Aerial Ace along with Pikachu's Iron Tail to knock their Pokemon to them and blast them off using Fire Blast, Greninja's Water Shuriken and Pikachu's Thunderbolt combination in an explosion. 
Braixen was released along with Serena's Pokémon and both Ash and Clemont's for a tea break and she was seen relaxing in the flower fields as everyone plays while she smells a single flower. During their relaxation, they heard Ash's Noibat screaming causing Serena, Ash and Clemont recall their Pokémon back. 
Braixen was seen arguing at Pancham about who's going to be brushed next as Serena brushes Eevee as Serena scolds them. Braixen is alongside Pancham and Bonnie watch them dancing at the party as well as Eevee and Pikachu's battle against Miette's Slurpuff and James' Inkay. Braixen is also happy to see Eevee evolved into Sylveon after she defeats both of their Pokémon with her newly learned Fairy Wind.
Braixen was used in the Fleurrh Rookie Class Showcase. She and Pancham participated in the Theme Performance, in which Performers had to place the highest number of Rhyhorn on their part of the field before time ran out, but they merely watched as the Rhyhorn came running by themselves to Serena's side. She danced alongside her teammates and ended the performance using Fire Blast combined with Sylveon's Swift, which formed a star briefly before exploding. After winning the Showcase, she and the others were congratulated by their friends with a feast.
Serena finally released Braixen to light up the cave using her twig to serve as a torch.  After helping Serena to get the three Princess Keys needed to compete for the title of Kalos Queen, Braixen was used in the Gloire Master Class Showcase. During the first round, she was grouped with Miette's Slurpuff and Sara Lee's Glaceon. Braixen used Flamethrower to create swirling flames around her and Serena, while the two danced. She then finished their performance with a star-shaped Fire Blast. Her performance was well received by the audience and she received the most votes, allowing Serena to advance to the next round. She was used in the final round along with Pancham and Sylveon. After creating beautiful sparkles by combining her Flamethrower with Pancham's Dark Pulse and Sylveon's Swift, Braixen and Serena created a ring of fire using Braixen's branch. After being lifted up by Sylveon's Fairy Wind, Braixen, Pancham and Sylveon combined their moves once again to create a giant blooming fire flower. Their performance impressed the crowd. However, it was not enough to defeat the opposing team, formed by Aria, her Delphox, Aromatisse and Vivillon, causing Aria to keep her title of Kalos Queen. Before the battle against Aria, Braixen along with Sylveon and Pancham were surprised to see Serena had swollen her left wrist which she hurts herself during her performance in the semi-finals as Sylveon is the one who saved her using her ribbons to avoid her from falling into the ground and flips her to end the performance.
Braixen was released by Serena to aid both her Pancham and Ash's Pikachu to fight Team Rocket's Pokémon and she quickly defeats Jessie's Gourgeist with a single Fire Blast. After Team Rocket was blasted off by Pikachu's Thunderbolt, Braixen was happy that Lilia and her Buneary are safe as well as Clemont's Bunnelby. 
Braixen alongside Pancham and Sylveon were assisting Serena to get water to put Ash's high fever down after he gains flu during his heavy training with his Greninja and Pikachu at the river. They are later confronted by Jimmy and his Pikachu who wants to challenge Ash for a Pokemon battle. Serena tried to tell him about Ash's condition but he won't listen due to his rocker speech. She alongside Pancham and Sylveon watch Serena poses as Ash to battle against Jimmy and his Pikachu as they cheered on Ash's Pikachu. The battle was interrupted when Team Rocket captures both. Braixen teams up with Greninja, Sylveon and Pancham to deflect Team Rocket's Gourgeist and Inlay's Shadow Ball and Psybeam with their Water Shuriken, Flamethrower, Dark Pulse and Swift combination. After the explosion, Greninja releases both Pikachu using Cut. After Team Rocket was blasted off by the latter, Braixen and the others are impressed with Ash's recovery. 
When Team Flare began their assault on the Kalos region, Braixen helped Serena and the others fend off the giant roots that are investing Lumiose City. She was later sent out to fight against Mable and her Weavile when Serena, Mairin and Professor Sycamore arrived at the Lysandre Labs to rescue Chespie. She later battled several Team Flare Grunts and their pack of Houndoom in order to buy some time for Mairin to retrieve Chespie. However, the rescue mission was interrupted when Lysandre, the treacherous leader of Team Flare, activated the Giant Rock, absorbed Chespie, and formed into a destructive version of a Zygarde. But Braixen, along with everyone else, chased after the Giant Rock Zygarde and fights it in order to prevent it from reaching the Anistar City Sundial, which it intended on fusing with it so it will create an explosion that would destroy the planet and wipe off nearly every living being. While Ash and Alain rescue Chespie, Braixen protects Serena, Bonnie, and Mairin from the attacking roots of the Giant Rock Zygarde and after Chespie was successfully retrieved, Braixen joins in the final battle against Team Flare.
At the end of XYZ, Braixen, along with Serena, Pancham and Sylveon, began their journey in Hoenn.
- Braixen is Serena's first evolved Pokémon.
- Along with Serena's other two Pokémon, Braixen enjoys a certain aspect of Pokémon Performing. In Braixen's case, it's dressing up and performing as well.