I think it's pretty clear we're getting a 'history repeats itself' type setting. I mean it's BEEN obvious, but Miura is beating us over the head now.
Caska and the Priestess
Guts and the Skeleton Knight
Schierke and Flora
As for the rest of the cast, I think we're going for their connection to each of the Four Kings of the World, maybe Guts/Caska's child is their envoy.
Because to ME, how else in the fuck are Guts and the rest ever supposed to stand up to Godhand and the entire Fate bullshit.
The Idea of Evil has employed Godhand and Griffith, so why would the Four Kings not have their own chosen ones to combat that for the fate of humanity?
Because of their influence, Guts won't follow the same path as the previous King and it'll break the cycle.