Do you think in your au, Ingo would wish he could return to Hisui? Maybe even look into finding possible ways to return? And maybe Emmet stumbles upon an open book on legendary and mythical Pokemon with notes like "Dialga - ruler of time, Celebi - time traveler, Arceus??? - might have to call Akari for help on that one"
How do you think that would go, whether or not Ingo was actually serious? (Could've just been contemplating and decided against going back after writing the notes, but to Emmet, it would seem like Ingo was serious about leaving.) I had just seen your drawing of them being honest with each other about Ingo's return, and it gave me ideas for angst!
Hoookay! This is a very interesting idea :) I need to drop some of my AU lore to explain that drawing a bit
It's quite a bit of story in between, but to summarise the timeline first, Ingo disappeared when him and Emmet were around 30, and then returned around their mid-to-late 50's. That gives us a time span of around 20 years of them being separated.
Ingo not only became a pretty important person in Hisui, being a Warden and all, but he had built a new life and new home from the ground up. Friends, colleagues, probably even deeper relationships. After Akari fell, he really wanted her to feel welcome in Hisui, to make the transition period a little less harsh, seeing he had taken a while to get used to this life as well. Akari asks him to come with her to Mt. Coronet one day and suddenly, he gains back his memories, and while they explained a lot of things, they also left him very conflicted. If he could split himself into Warden Ingo and Subway Boss Ingo, he probably would, because both his home in Hisui, and his home back with his younger twin, were important to him. He did make a choice in the end, and while disappearing from the lives of others a second time hurt, this time he had a choice, and he figured it was the correct one.
Problem is, time didn't stop, and he landed in what would be his 'current' reality, so to speak. Maybe it would have been different if he were sent back to a year, maybe two years after his disappearance (And their ages would have drifted apart around 20 years), but as we know, Arceus loves being a drama queen.
Emmet had moved on during that time. Got married, had children, moved from their old apartment, that kinda thing. Put yourself in his shoes; What would you feel if your twin, who has been missing for two decades, declared dead, suddenly reappeared? The twin who you had to grieve, the twin you had to let go of, the twin who had been given a cenotaph? Imagine telling your kids. Imagine explaining that the uncle you told them about, who everyone assumed dead, suddenly turned out to be alive? You may feel relief, but you would be a bit angry, wouldn't you? It would be awkward, to suddenly have him as a part of your life again.
Their relationship would be EXTREMELY strained in the first few months, maybe even years of Ingo coming back. It only would really be softened by the fact that the first time Ingo disappeared was a complete accident, and that he didn't leave on purpose. They grew into completely different people than what they were while still together. They would fight and bicker over the smallest things, they would spew more hurtful words to eachother than they have ever before in their entire lives. They would find their 'new' brother so infuriatingly hard to exist with, it would feel like being forced into a room with a stranger.
Would Ingo want to return to Hisui? Before they finally worked through stuff, yes, definitely, but it would be more of an impulsive thought than an actual plan. He still loves his brother a lot, despite everything, and he did miss him, Nimbasa, and the Subway overall. It's just that he has so much catching up to do (especially on the fact that he's a brother-in-law and an uncle now, yay) and he has to accept that Emmet is different than he remembers. It's overwhelming.
It's overwhelming for Emmet, too. Same as for Ingo, not only does his brother seem like a completely different person, it's nuts what 2 decades without modern technology does to a man. Can you imagine letting Ingo into a server room now? Or doing any maintenance around a newer train? Plus, he now has a family outside of his brother to look over. Safe to say, it would be frustrating, and he would definitely feel like the stable life he managed to build suddenly got uprooted.
If Emmet did find such a book, or found out Ingo had planned to leave again, there would be a fight of the century. No doubt about it, the fact that he even thought about it would be enough to anger him. Make with that what you will, I personally think it would be a screaming match, but one that's definitely needed for them to finally reconcile.
Later on in the AU they do finally find common ground and learn to live with eachother again, albeit Ingo lives in their previous apartment and Emmet lives with his family. They're still twins, brothers, but they're not as inseparable as they were before, they grew too far apart. Besides, being independent is more in line with who they became over time! :]
The drawing itself would be somewhere in that period between them being tense about eachother's presence and finally reconciling. It's a little late for me so sorry if these ramblings are a bit hard to understand, feel free to ask anything else as a follow up!