So we know that Nolan was the son of Emperor Argell and that he was the heir to the throne of Viltrum. And when his father was murdered no one knew who Nolan was and their society fell into chaos. But how did no one know who he was? Why wasn’t Argell raising his heir and telling people who he was? Also, I’ve heard that Nolan had half-siblings is this right?
It’s possible that he was one of many heirs and that there was no one specific person meant to inherit the Empire until selected. Another possibility is that he wasn’t a direct heir to him but rather two or three generations removed, meaning that Nolan’s parents would have very potentially not even realized his lineage. The last and, in my opinion, most likely explanation is that Robert Kirkman didn’t specifically plan out all of the minutiae of the series and just left this to the waist side or thought it up later