I have totally thought about this. Cassian has so much potential and we really get to see his soft side in ACOSF but yes, I wish that we got to see more of the other stuff. Like I think we saw more of Nesta because this was Nesta’s book and healing arc which I loved, and I loved the Nessian, but it was so glossed over all his history and trauma. Like we got perhaps these three paragraph chunks of monologue of him remembering the stuff he’s been through.
That being said, I don’t think Nesta or Cassian’s story is even close to being finished. She got the ball rolling with them, especially Nesta, and all the unknowns. Now I keep thinking about the High King plot mentioning. And Rhys is literally like I don’t want it (Nesta also admits she doesn’t care about her powers or ruling the world so I thought that was an interesting parallel).
I think there is going to be a war because it’s always a threat in the back of the mind for all the characters, especially now that Koschei has revealed himself to be a big enemy. I believe a possibility is once war ends, Illyria will be ravaged, and it’s not going to be enough for Rhys to handle both his court and Illyria. Nesta and Cassian may have to become it’s rulers (white savior trope aside with Nesta) OR something happens and they become High King and Queen since Rhys is adamantly against it.
I just feel like constantly hearing about how Nesta is a Queen of Queens or queen triumphant and Cassian was a brooding warrior prince and Prince of Bastards falls short in ACOSF if neither of them ascend to some kind of royal title. So I think they will in later books and ACOSF is just the beginning. It would also really help to have two warriors like them in power because like you said, the Valkyries would be respected. Also they’d have an unstoppable war force with both the Illyrians and Valkyries under their command.
Thanks so much for the input @nestaa-stan, I totally want Nesta and Cassian to become rulers, not just for the foreshadowing and bc they’re my fav ship and couples, but because I think they’d do so well as leaders.