Beloved Tyrant

I took in a knight who was about to be executed for taking part in a rebellion as my s*ave.
I tried to return his status as a noble and duke, but..
“Please do not refer to me as “sir”. I am not a knight. You needn’t speak formally to me either. I am not a noble.”
“…….”
“I am simply Your Highness’ s*ave.”
Somehow, he is being strange.