I was thinking that way because I've noticed that when you select a stage without selecting the BGM, the stage is directly associated to a BGM/character! That's why I posted that way, but I can be wrong!
I noticed that too - on that vid, Seig's portrait appeared in a blue bar up to the right of the Castle Under Seige stage card - it defo looks very likely that each character is allocated their own stage, or at least each stage has a "main" character. As the player scrolls through all the cards, the characters appear as follows:
Castle under Seige - Seigfried as the main, with Voldo and Ivy as secondary options by the looks of things - but I think this is just for their music, as it says "Voldo's theme".
Townsquare - Patroklos (apologies for doubting this earlier in the thread!) The other slots are "locked"
Moonlight wasteland: Tira. Hilde is one of the secondary slots and the other is "locked" (for Zwei, probably)
Merchant Ship: Maxi, with Voldo and Mits as the secondary slots.
Torture Chamber: Voldo, with Seig and Maxi as the secondary slots.
Coliseum: all "Locked", but probably Pyrrha.
The Evil Shrine & Kunimitsu temple did not appear, but I think we can safely say Astaroth and Natsu respectively.
Luoyang will be Leixia's stage, I think that's pretty certain too.
That cavern stage - Raph possibly, because of the bats as Gabe says.
Burning Old Town - Nightmare, I reckon. I think they'll probably do an actual Venice stage for Ezio, as they did for the previous guests (that wretched hangar stage!).
