Okay so you know how being a royal mistress wasn't actually a title/position (at least, not until 15th century France) and a mistress usually had an official place in court, usually as part of someone's entourage, a governess, etc., so imagine Arthur visiting another kingdom for diplomatic relations and being like, "this is Merlin, my manservant" which is perfectly normal, all kosher, until they see Merlin and Arthur being...well, Merlin and Arthur and they're collectively like, "Ohhh, that's his manservant ;) gotchu fam" and Merlin is innocently oblivious as to why everyone's being so nice to him now whilst Arthur is like "Yeah, good question" *squinty eyes*

bestie imagine them probing Arthur for the deets like "so, your manservant is always by your side? 👀" or "he reads your speeches?" and Arthur is stuck because they're asking him this during dinner and Merlin is right there standing next to him totally oblivious (not for long i feel). like his inner dialogue is literally "are...are they implying...what i think they're implying...no....yes?"