Wanderer has moved on from everything that happened and was healing from what happened in his past with Nahida, the Dendro Archon's help when he suddenly got sucked into a portal leading him to another world where he was Raiden Mei, the hi3 storyline goes from there but in teyvat everyone from sumeru and traveller is set out looking for him (lmao poor traveller twin) when suddenly everyone from sumeru to put into a room with Raiden Mei aka Wanderer (before APHO so Mei's still a Herrscher)

There is Traveller, Paimon, Nahida, Cyno, Tighnari, Collei, Alhaitam, Kaveh, Nilou, Dehya, Candace and Dori in the room with the current Wanderer aka Raiden Mei

Nahida: What..?