Tell your father to investigate
From Lord Of Utterdom
"I don't think it would harm anyone to look into the rumors," you say, smiling to the Duke, who in return looks relieved. "Peasants may chatter endlessly and spread rumor, but even those rumors must have some basis in something."
The king squeezes your shoulder, nodding. "Then I suppose we shall investigate, to see what truth this foul rumor holds. I suggest we keep this quiet from the Duke of Sharen." He glances amongst the faces in the room. "Should the rumor turn out false, he'll think we question his loyalty. Should it turn out true, it would be best he did not know we knew of his intentions."
The Duke thanks the King and you both, and lavishes the two of you with praise. The king excuses he and his wife, asking them to seek the main hall and enjoy some wine while they wait for him.
When they are gone, he turns to you.
"You were late," he says in a stern voice. "So now I will task you with this, to spare me the headache of having to watch you waste more time on wine and women." You beging to protest, but he holds up a finger. "No, you will do this. If you are to be king someday, you must prove you have the intelligence and resolve to adminster the kingdom. So I suggest you gather your things, and prepare to travel."