Their development could involve a change in their goals. Instead of just focusing on stealing Pokémon for Team Rocket, they could start to care more about the well - being of all Pokémon. Saving Ash could make them realize that there are more important things than their previous missions. They might even form an alliance with Ash and his friends, leading to new adventures where they use their combined skills to protect the Pokémon world.
Well, perhaps Ash is in a different dimension or a strange, uncharted area where he's in trouble. Jessie and James could be on a mission of their own in that area and stumble upon Ash. They realize that they need to save him because, despite their past differences, they know Ash is important to the Pokémon world. They might have to combine their resources, like Jessie's Wobbuffet and James's Cacnea, to fight off any threats and get Ash back to safety.
The main characters are clearly Ash, Jessie, and James. Ash is the one doing the saving, while Jessie and James are the ones being saved.
Luke would likely develop a more serious and responsible side. He'd have to grow up quickly to be a good father. Jessie might become more nurturing and also more assertive in making decisions for their future. For example, she could demand that Luke be more involved in the pregnancy process, like going to doctor appointments with her.
Ash is usually very positive and determined. In Jessie's body, he might try to bring some of that positivity to Team Rocket, which would be a big change for them. Jessie, on the other hand, is more devious and cunning. In Ash's body, she might be more aggressive in Pokémon battles, using strategies that are a bit more underhanded at first until she realizes that Ash's way also has its merits.
I'm not sure specifically as there could be many different versions of such a fanfiction. But generally, it might be about Ash coming to the rescue of Jessie and James in some sort of dangerous or difficult situation they are in within the Pokémon universe.
Zoey might become more nurturing and selfless as she is about to become a mother. James could develop a stronger sense of responsibility and protectiveness towards Zoey and the unborn child.
In the 'jessie and james adopt ash fanfiction', perhaps they would start living in a different kind of home. Since Jessie and James are from Team Rocket, they could use their resources to give Ash a more luxurious or unique living environment. And Ash could introduce them to his Pokémon friends in a more personal way. He might also learn some of the sneaky tricks that Jessie and James know, which could be both good and bad.
Meowth would probably be overjoyed. He has been with Jessie and James for a long time and would see their marriage as a great thing. He might be more helpful than ever, running errands for them and even trying to cook for them using his little paws. Their other Pokemon like Ekans and Koffing might be a bit confused at first but would soon get used to the new situation and be protective of their new 'family'.
For Harry, he would gain a new sense of family and belonging. Meeting his parents would fill a huge emotional void. James might develop from being just a memory to a real - life mentor for Harry, teaching him about his family's magical heritage. Lily could develop into a source of great emotional support for Harry, and also show her strength as a witch, which Harry might not have fully known before.
Perhaps a major plot twist would be that Ash starts to act more like Jessie and James. He might become a bit more mischievous or devious in his ways of catching Pokémon. This would be a huge change from his usual good - natured self. Also, there could be a plot twist where the three of them find out that they are related in some unexpected way, like they share a long - lost family connection. This would add a whole new layer of complexity to their relationship and the story as a whole.