Inn:
Klaire (TUNDERTALE*)
Reese (TUNDERTALE)
Dawn (TenSura)
Raven (TenSura)
Inn (unaccounted for):
Noah (Metroid), Cervelax (Terraria), Esther/Navy/Roxas (Floralis), Viridian (Floralis), Butter (Floralis), Jeff (Metroid (Zebes)), Issac** (Shadowfell), Aden (Kirby), Quilaren (Chir''s world), Kessica (Chir''s world)
Forest:
Lukas (Swaasnia)
Xaxen (Shadowfell)
Ant (Generic fantasy???)
Forest II:
Pixy (pixelation)
Dozo (pixelation)
Trinity (???)
* Terraria-UNDERTALE.
** May be counted with Xazen? Probably not.
Inn:
Just mentioned characters: Mix of Terraria, UNDERTALE, and TenSura logic most likely, plus whatever innate universe the inn belongs to.
All characters in the inn: The above, plus at least Metroid, Floralis, Chir''s unnamed world and a bit of Kirby.
Forest (group 1):
Mix of Swaasnia (Lukas), Shadowfell (Xazen), and generic fantasy (Ant).
Forest (group 2):
Pixelated (Pixy, Dozo) + Floralis (Trinity).