[There's an exasperated, overly loud sigh from the opposite direction. Mycroft's rolling his eyes.]

Really.

[He rubs his forehead though, he's not at all comfortable with the very notion that he cannot trust his own eyes, nor the fact that it was something to be expected. It seemed so real. He can only continue on with the subject and be patient with the fact that little brothers are little brothers.

Well. If his own formidable mental faculties were tricked by whatever was causing, then it likely affected everyone else as well, with their ordinary minds. Made him feel slightly better.]

Explain. What other hallucinations-- [The word drips with disgust.] --have you seen? Other than, you know, if you indulged in old habits.

[He couldn't be sure if Sherlock had done so or not, but he wished to test his reaction to assess his mental state on the matter.]