Serena (Japanese: セレナ Serena) is a traveling companion of Ash who debuted in Kalos, Where Dreams and Adventures Begin!. Her first Pokémon was a Fennekin that she received from Professor Sycamore.
As a young child, Serena was sent to Kanto, against her will, to attend a Pokémon Summer Camp, which was hosted by Professor Oak. One day, while at the camp, she got lost in a nearby forest and was startled by a Poliwag, falling over and hurting her knee. Then, she met Ash Ketchum, who was looking for the same Poliwag and spotted Serena. Noticing her knee injury, he pulled out a handkerchief and wrapped it around her wounded knee, saying that it is a good-luck charm and that the pain would go away. However, when Serena's knee continued to hurt, Ash told her "Don't give up till its over" and helped her up before escorting her out of the forest. Afterwards, she returned to Kalos, bringing along the handkerchief and the memory of her meeting with Ash.
Serena made her first onscreen appearance in Kalos, Where Dreams and Adventures Begin!, where she was forcibly woken up by her mother's Fletchling. In Lumiose City Pursuit!, she attempted to practice Rhyhorn racing after being encouraged by her mother, a famous Rhyhorn racer herself. However, Serena's attempts at controlling her mother's Rhyhorn ended with her being sent crashing into the ground.
Later that evening, Serena complained about her earlier practice leaving several scratches on her face. She sat down to watch a news report on an incident that was occurring in Lumiose City. On the screen, she saw Ash trying to calm down a rampaging Garchomp at Prism Tower and recognized Ash as a boy she had known in her childhood. The next day, while feeding Rhyhorn, Serena thought aloud that something interesting was going to happen and that it involved Ash.
She began her Pokémon journey in A Battle of Aerial Mobility! when she set off to Professor Sycamore's lab in Lumiose City. Immediately upon arriving, Serena questioned the Professor about the boy on television and he confirmed that it was indeed Ash Ketchum. However, to Serena's disappointment, Ash had already left Lumiose City the previous day. Serena was then offered to choose her starter Pokémon.
In A Shockingly Cheeky Friendship!, Serena chose Fennekin, received a Pokédex, and started her journey. Later that day, she continued to travel with Fennekin, but didn't want to camp out for the night after seeing some wild Venipede. She was attacked by a wild Vespiquen that she mistook for a person, only for Fennekin to scare Vespiquen away. Afterward, Serena met a Nurse Joy, who told her where to find the nearest Pokémon Center.
In A Blustery Santalune Gym Battle!, she finally reached Santalune City and found Ash during his gym battle with Viola. She introduced herself to him, Clemont, and Bonnie, after returning his backpack when it was left behind at the Gym. At the end of the episode, she asks Ash if he remembers her, at which point the episode abruptly ends.
In Battling on Thin Ice!, she revealed that the two of them met at the Pokémon Summer Camp when they were younger. Although Ash remembered the camp, he didn't specifically remember meeting Serena, much to her disappointment. Serena quickly regained her composure and reminded him that he once told her to never give up. Hearing these words helped Ash continue his training in order to win the rematch against Viola. During the rematch, Ash was visibly becoming overwhelmed by Viola's battling strategy, but Serena yelled at him to never give up. The inspiration that he had once given Serena was now being given to him, and these words encouraged him to continue the battle. At the end of the episode, after winning the Bug Badge, Ash asked Serena what her plans for the future were.
Serena officially began traveling with Ash and his friends in Giving Chase at the Rhyhorn Race!. This was when Serena revealed why she began her journey in the first place. After seeing Ash on TV, she decided that she would begin a Pokémon journey in order to return the handkerchief he used to mend her knee injury. After she returned the handkerchief, Ash remembered their encounter and called her the "Girl With the Straw Hat."
Later on, Serena helped teach Ash how to ride and race on a Rhyhorn when he expressed an interest in Rhyhorn racing. While doing so, Serena's opinion on Rhyhorn and Rhyhorn riding quickly changed when the Rhyhorn were very friendly towards her. Later, while she was helping Ash learn to ride, she called out similar words Serena's mother had yelled to her during her Rhyhorn riding lessons at home. At that moment, Serena realized that she had misjudged the sport of Rhyhorn racing and that perhaps she did not hate it as much as she thought. Serena expressed in the same episode that she did not dislike Rhyhorn racing but that she wanted to find a goal that she likes even more.
The next day, Ash was captured by Team Rocket and Serena had to help rescue him. This was when Serena had her first Pokémon battle, commanding Fennekin to use Ember on the criminals. At the end of the episode, she gave Ash a pouch of cookies, saying it was her way of thanking him for all he had done for her.
In Clemont's Got a Secret!, Serena learned from Clemont's father, Meyer, that Clemont is the Lumiose City Gym Leader. Although initially angry with Clemont for keeping this secret from her along with Ash, she helped take back the Gym from the malfunctioning Clembot. She battled Clemont's Magneton with her Fennekin, but it managed to avoid Fennekin's attack, forcing Pikachu and Froakie to step in and defeat it. Later, she watched Clemont battle and defeat Clembot for the control of the Lumiose Gym.
In A PokéVision of Things to Come!, Serena decided to participate in PokéVision, which is similar to making PR videos. Trainers promote themselves and demonstrate their bond they share with their Pokémon by dressing up and creating a short video. After watching some sample PokéVision videos in the Pokémon Center, Serena took to the idea of being able to make one of her own with her Fennekin. She rented a camera and began filming with Fennekin. The two of them dressed up in multiple outfits and the video featured them posing and baking together. However, during the filming of the video, Fennekin was captured by Team Rocket. Serena was able to rescue Fennekin, and in the process she remembered all that they had been through together. Her feelings of friendship were conveyed to her Pokémon, and Fennekin was able to learn Flamethrower in the battle against Team Rocket. After this event, Serena was able to finish her filming and was proud of her final product.
In A Battle by Any Other Name!, Serena participated in a Poké Puff competition, but she did not emerge victorious. Before the event, she met another competitor named Miette. The two of them compared their Poké Puffs to see whose were superior, which led to a spark of rivalry between them. After comparing the two Poké Puffs, the group realized that Serena's Poké Puffs were more suited for human's tastes than Pokémon's. This was part of the reason that Serena was not able to win the Poké Puff competition.
Serena had her first official Pokémon battle in Summer of Discovery! against Shauna. Shauna and her friends, Tierno and Trevor, had seen the PokéVision video that Serena filmed in Lumiose City and recognized her from it. Serena accepted Shauna's challenge, and alongside Fennekin she faced off against Shauna and her Bulbasaur. Unfortunately, Serena was unable to win despite having a type advantage. Serena talked with Shauna throughout the episode, and learned that Shauna was aiming to be someone who could put on performances with Pokémon. Her conversations with Shauna were a catalyst in helping her realize that she was the only one of her friends that didn't have a set goal. At the end of the episode, Serena sat alone brushing Fennekin's tail and wondering what her dream was.
In Day Three Blockbusters!, Serena and Shauna had a conversation. Shauna informed her about Pokémon Showcases, festival-styled tournaments in which Trainers known as Pokémon Performers perform together with their Pokémon on stage. Shauna told Serena she was planning on becoming a top-class Pokémon Performer herself, and this inspired Serena to become one as well. In Dreaming a Performer's Dream!, Serena witnessed her first official Pokémon Showcase. She saw a performance by top-class Pokémon Performer and Kalos Queen Aria, and witnessed a wild Pancham causing a ruckus on stage. Later, outside, the Pancham stole Ash and Clemont's belongings. Serena managed to track Pancham down and witnessed how it put on a performance with no one around. This made her realize Pancham loved performing and wanted to show this to everyone. With this in mind she announced to her friends she wanted to capture it. Battling with Fennekin, she managed to weaken and successfully capture it. After capture, Serena gave Pancham a pair of her favourite sunglasses.
Serena has a love for fashion and clothing. An early example of this is in A Battle of Aerial Mobility!, when she spent time carefully selecting an outfit and was troubled over which of two hats looked best. Serena then asked her mother, who selected a beret. However, Serena promptly tossed the beret aside and picked up the other hat, saying that whatever her mother did not choose was certain to be the cuter one. Later, in Giving Chase at the Rhyhorn Race!, Serena expressed excitement about visiting the clothing boutiques in Lumiose City. In A PokéVision of Things to Come!, she was eager to dress up in many different outfits while making her PokéVision video.
Serena also seems to like baking and is quite skilled at it. An example of this was demonstrated in Giving Chase at the Rhyhorn Race!, when she stayed up late at night to bake cookies for Ash and the gang, which they seemed to enjoy. Also, in Mega-Mega Meowth Madness!, she had baked some macarons for the group, but they were stolen by a Chespin. In A Battle by Any Other Name!, she also participated in a Poké Puff baking competition.
Since the start of the series, Serena has proven to be a kind and polite girl. However, in Kalos, Where Dreams and Adventures Begin!, she was openly rebellious towards her mother. She refused to wake up when her mother ordered her to and gave a sassy response to her mother's call to watch the news. This tumultuous relationship was best demonstrated when Serena's mother made her practice Rhyhorn riding, which she had hated doing.
While she genuinely cares for her Fennekin, as well as the well-being of other Pokémon, Serena has expressed little ambition towards becoming a full time Pokémon Trainer. In Going for the Gold!, she did however attempt to capture a Corsola, which she thought was cute, but was unsuccessful due to Fennekin's type disadvantage and Fennekin's unwillingness to fight.
As of yet, Serena is uncertain what paths or career to pursue in life. Although she possesses a diverse and well-rounded skill set, she is still undecided about what best suits her. Fortunately, her travels with Ash, Bonnie, and Clemont have afforded her a chance to find herself and explore her options. In Summer of Discovery! Serena began to think that not having an established goal was a problem. After losing her first official Pokémon battle at Summer Camp and seeing how passionate the Trainers around her were, Serena began seriously considering what she wanted to do with herself and her Pokémon.