"Well, if that's how it is than that's how it is."
Deceiving others was easy when no one really wanted to believe what you had to say.
"I wanted to thank her formally, but when I asked, my father swept everything away. It was a really strange state of affairs however I don't think he wanted the people to know that the empire needed an outsider to help manage state affairs."
Prince Benidict wasn't the savviest of men, but his formal education served him well. His assumption was almost correct, however the emperor was aware of something that the third prince wasn't.
Onyx Holm's head of state was aware of the existence of the lord of Dyne. While not certain, in absence of stewards or magic, they only answer could be the dark cursed monsters of Dyne. Since the person hadn't made grand moves against the empire it was simpler to not admit about it and focus on distant wars and other crises.