I think L visits Lumiose again, passing through as he wanders to new places. It's been decades and the city is as different as it is the same. Maybe Prism Tower was rebuilt. Or maybe the city left the ruins of Ange untouched, a monument to the mistakes of the past.
Hotel Z looks the exact same on the outside and not too noticeably different on the interior, either. Furniture pieces have changed, walls have been repainted, new decor pieces added, and yet it's all in a similar style to how he remembers it. There's plenty of guests, primarily teenagers and young adults. A young woman greets him from behind the counter, not even a spark of recognition in her eyes, and asks if he needs help. L asks if the owners are around.
The management office is small and cluttered with decorations. Years upon years of smiles frozen in photographs. A well-worn and well-loved green jacket, retired before it could fall apart completely, in a shadowbox. The front page of a fashion magazine, advertising the hottest new designer around. A flier for a dance production at the city's biggest theatre.
The person behind the desk is both recognizable and also not. Grey streaks run through their hair, lines visible on their face. Reading glasses are perched on their nose and a gold Mega Ring on their wrist. Their sense of fashion has evolved but their love for it is unchanged. A Floette floats next to them, seemingly assisting with their work.
They greet him as an old friend and insist on setting him up with a room for the duration of his time in the city. The others are still co-owners of the building but are too busy with their own careers to help with the day-to-day management. Running the place with just Floette isn't a problem, though. There's a lot of good that they're doing here, making the world a better place.
'Hotel Z' is a bit of misnomer these days, they tell him. A hotel is a business but Hotel Z is a shelter for those who have nowhere to go. It's funded both by the CEO of Quasartico and a healthy amount of donations. Their biggest donors include the owner of Hotel Richissime and a shady loan business, while a local construction company does building maintenance at a discounted rate.
They tell him that Zygarde is no longer by their side, as it had to return to its duties as a guardian of nature, but sometimes a four-legged black Pokemon will pay a visit to Hotel Z.
The pair find themselves walking the streets as his friend tells him how the city has changed. There aren't as many Pokemon, since they're no longer being drawn in by Mega Power, but still a lot more than most cities. Many of these Pokemon roam the streets freely, living happily alongside humans. Maybe there's a few Wild Zones left, for those Pokemon that the city just can't safely exist alongside, but there's a sense of deliberate planning to these zones. The construction must have been aided by well-informed researchers.
There is the occasional incident with the wild Pokemon, his friend concedes, but they prepared for that. The people of Lumiose City are strong enough to live side by side with them. Rumor says a few humans can even go toe-to-toe with the Pokemon themselves.
They stop at a cafe and his friend overpays on purpose. Most customers who can do so: it helps the cafe recoup the cost of how much they give away to those who can't afford to pay. Most of the employees of the cafe are too young to know the name 'Team Flare' as anything other than a piece of history.
The walk ends at a large grave, something that L himself won't have for at least another 2900 years. His friend might have one before he can see them again, though. It's been a good portion of their lifespan already, after all. His friend is aware that this could be the last time they see each other and they're just glad they had a chance to show him everything.
It took years upon years and many hands to make all these changes. It's still far from perfect and it's only one city. There are things people are still working on, with no guarantee that they'll live to see the fruits of their labor. It takes time to change the world but it's a worthy endeavor. His old self lacked the patience to see this progress but his vision's far clearer now.
If all this could be done within a normal person's lifespan, who knows what the world might look like when his time is up?