While there have been many characters and relationships presented in the Pokémon anime, events in XY&Z may have been a game-changer for Pokémon's charismatic hero, Ash Ketchum. During the events of XY&Z, Ash travels with Clemont, Bonnie, and Serena as they explore the Kalos region. However, Ash's relationship with Serena takes a romantic turn as she struggles with her crush on him, and Ash slowly becomes interested in Serena beyond friendship.
Ash and Serena's relationship starts out primarily one-sided. Serena remembers Ash from their first encounter as children at professor Oak's Pokémon camp, where he lends her his handkerchief to protect her knee after she has fallen down. Serena keeps the handkerchief for years after, hoping for a chance to return it to him. When she sees him on TV one night at the start of the Pokémon XY anime, she sets out to meet with him, not knowing how it will alter the course of either of their lives.
Ash and Serena grow very close through their adventures in Pokémon's Kalos region. While Ash appears oblivious to Serena's feelings, Serena continues to find her own feelings deepening, and starts to make bold changes in her life as he inspires her to try harder. Ash begins to develop his own personal feelings for Serena, even giving her a special gift in episode 59 of Pokémon XY, when they are both beside the pledging tree. The gift he gives her is a special blue ribbon that she then wears as part of her outfit for the rest of XY&Z starting in Episode 60.
Pokémon's Ash And Serena Kiss While Saying Goodbye
Thanks to a fan translation shared on Reddit, Pokémon fans were able to learn more about the emotional end to the Pokémon XY&Z anime, and the moment that Serena says goodbye to Ash and Pikachu. As Serena prepares to leave Kalos, she tells Ash that she wants to be more like him, before stepping onto the escalator in farewell. However, she turns and dashes back up the steps as viewers get a slow-motion scene of Ash and Serena's feet as she goes up on her toes. When she pulls away, she is blushing, and Ash looks awestruck, while Clemont seems embarrassed in the background. After translating an interview in AnimeStyle magazine with Yajima Tetsuo, a director of Pokémon XY&Z, it is revealed that a kiss implied to happen during the scene.
While Serena hasn't returned in recent seasons, there is hope within the Pokémon fandom that the relationship between herself and Ash will be revisited in future episodes of the anime, or movies. It's hard to say what the future could be for Ash and Serena, as the Pokémon anime doesn't usually age the main characters, or cover what happens when they grow up. However there is always a chance that Pokémon fans will have a chance to see Serena again in future cameo appearances, and hopefully add to the relationship between herself and Ash.
Source: Artoo_Detoo/Reddit