Ahaha. That would be Sherlock Holmes and Viola from Twelfth Night. TN is Holmes' favourite Shakespeare play, so he knows about her, but not vice versa. Also it would take Viola some time to explain to him that she isn't an actress but in fact the character herself, and Holmes would argue the impossibility of that. She'd probably get him by way of explaining that he's a fictional construct himself once he mentions Watson's stories. Viola would probably find him a bit off putting at first but we all know she can hold her own in a verbal duel, and she'd argue with him just for the sake of it.