Veitaru must be one hell of a smart kid to be able to see through the adult Royal Spymaster (who's been in the business long before Vei was born) like that, not to mention having already figured out Cain was a separate entity from Frore and being thoroughly unimpressed with the both of them. Cain must truly have been a terrible spymaster to be able to fool, frighten, or even catch the attention of nobody.