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?
My guess is overconfidence.
Argall was probably the only one left alive who knew, because he’s an immortal unstoppable Viltrumite king, right? He’s the only one who NEEDS to know. In another 10,000 years or whatever, he might be feeling a little older and is ready to step down, then he’ll tell whoever he needs to that Nolan is the heir.