Well, perhaps Ash comes back with new skills and a sense of purpose. He might be determined to protect Serena even more than before. In the fanfiction, he could use his war - learned strategies to deal with any threats that come their way. And their relationship could evolve into a deeper, more mature love as they face new challenges together.
In this fanfiction scenario, Ash returning from the war could also bring some conflict. His newfound self might not be fully accepted by Serena at first. She may have expected the old Ash. But as time passes, they start to understand each other better. Ash could share his war stories with Serena, which in turn makes her see him in a new light and strengthens their bond.
Well, one possibility is that Ash has changed a great deal due to the war. Maybe he has new skills or a more hardened personality. He could struggle to fit back into his old life with Serana. For example, he might be haunted by the memories of the war and find it difficult to be as carefree as he once was with her.
It could be a bit rocky at first. Ash may have seen and done things in the war that have changed him. Serena will need to adapt to this new Ash. But if they communicate openly, their relationship can grow stronger. For example, if Ash has post - war trauma, Serena's support can help him heal, and this shared experience will bring them closer.
Well, perhaps Ash returns physically but is emotionally scarred. Serena would be there to comfort him. They could start by just reminiscing about old times. Then, Ash might introduce Serena to some of his war - time comrades who are also Pokémon trainers. This could lead to a whole new set of storylines involving group adventures, Pokémon battles, and the rebuilding of relationships that were strained during the war.
Perhaps he'll share his new adventures and the knowledge he's gained from traveling different regions. He could inspire the new generation of Pokémon trainers in Pallet Town to aim for greater things.
Ash and Serena might meet some new and strange Pokemon in the hospital's garden. These Pokemon could have unique abilities that help in their recovery. For example, a small, furry Pokemon that can emit a soothing glow.
Another possibility is that Ash returns with some sort of special mission or knowledge from the war. He might be on a quest to use this new - found knowledge to make changes in his homeland. He could face opposition from those who don't believe in his ideas or are afraid of the changes he wants to bring. This could lead to a story full of adventure and self - discovery.
In this fanfiction, Greninja might come back with new powers. Maybe it has been on a special training journey and returns to Ash to help him in a big battle.
One possibility could be that Ash comes back from war a changed man. He might have seen a lot of hardships and death, which makes him more mature. When he reunites with Serena, their relationship could be a bit strained at first. Maybe he has some PTSD and Serena has to help him through it, and in the process, their bond deepens more than ever.
They might encounter advanced Pokémon species that don't exist in their time. For example, new evolutions or completely new types of Pokémon. This could lead to new adventures and challenges as they try to understand and befriend these Pokémon.
In this kind of fanfiction, they might have new adventures. They could explore the unique Alola region together, encounter new Pokemon species, and bond even more deeply. Maybe Serena would learn new battle strategies from Ash, and they would participate in local Alola Pokemon contests and battles side by side.