One possibility could be that in the fanfiction, Ash betrays Latias out of a misunderstanding. Maybe he was tricked by a villain into believing that Latias was a threat to the region. This would create a lot of drama and conflict in the story as Latias, who probably trusted Ash, would be deeply hurt.
In fanfiction, a story about Ash and Latias being betrayed could be really heart - wrenching. Maybe it could involve Ash being wrongly accused by his friends and Latias being forced to turn against him due to some dark magic or false information. It might explore themes of trust and friendship being broken.
Through shared adventures. For instance, if they get lost in a mysterious forest together. Ash would rely on Latios or Latias's ability to sense their surroundings and they would grow closer as they face the challenges of finding their way out. It could be as simple as Ash sharing his food with them during this time, showing kindness.
Well, it often starts with curiosity. Latias might be intrigued by Ash's determination and kindness. So she starts to observe him from a distance. Then, as she gets closer, Ash might notice her presence and start to interact with her. Their relationship grows as they face challenges together, like battling other trainers or saving Pokemon in danger. Eventually, it can turn into a deep friendship or something more romantic in some fanfictions.
One possible fanfiction could be that Ash stumbles upon Latias in a hidden, mystical forest. Latias, being curious about this strange trainer, allows Ash to approach. Ash, with his kind heart and determination, manages to earn Latias' trust. He then throws a Pokeball, and after a tense moment of the ball shaking, he successfully catches Latias. This could lead to new adventures as Latias' unique abilities open up new areas for Ash to explore.
Adventure is also a popular theme. Many fanfictions take Ash and Latias on exciting quests, whether it's to find a lost Pokémon or to solve a mystery in a new region. Their combined skills and unique abilities make for thrilling adventures.
A possible scenario for their betrayal in fanfiction is that a powerful organization kidnaps someone Ash loves and forces Latias to betray him as a ransom. Latias, with no other choice, has to do what the organization says. Ash would then be left feeling betrayed, not knowing the real reason behind Latias' actions at first. This could lead to a story full of mystery, action, and ultimately, redemption.
I don't think they are overly popular. Most Pokémon fans are interested in the positive aspects of the Pokémon relationships, like friendship and cooperation. Lemon fanfics, which often involve inappropriate content, are not something that the majority of the community would support or promote.
I'm not entirely sure specifically what that fanfiction is about as I haven't read it. But generally, it might involve the character Latias interacting with Ash in some sort of manipulated or unique situation within the fan - created story.
One story could be that Ash and Latias meet in a forest. Ash is initially confused by the unique Pokemon that is Latias. Latias is shy at first but then starts to show Ash around the forest, leading him to discover some rare berries and a hidden Pokemon nest.