I'm curious as well about the character's backstory and each different connect that it brings to how they ended up all becoming apart of the vanguard and how each of them made it to becoming part of the S-class vanguard. I feel like they have a hidden secret that they have just like our protagonist but what has driven them. How did they meet the qualifications to becoming S class and what would be the requirements. Maybe some strings behind the scene were pulled and maybe they are being watched closely by this hidden group and set this group together knowing there must be a connection to each character. The protagonist sister is not being considered s class known to most people but more hidden as the fox... hmm could she have played a part and the past makes it even more confusing for the fact that she could be working for the other side and the protagonist was unknowingly part of the other side but grew up thinking of being a non-antillian sort of simliar to icarus. Strange enough we know where most of the character came from or originated but its suspicious that the protagonist has not been given a specific place they came from.Could it be that the protagonist be a child that was swapped with the princess between the two countries and serrani took the protagonist from antillian since they were orignally the king's daugther? King William could be the sibiling(or father) of princess lily or maybe that might be my odd thinking because of the hair color. Also the "Black wing" sounds kind of like code for someone we have yet to meet but oddly enough it might be someone that may have been mentioned already but that might just be some guessing from my part.