Poprishchin describes how the grand inquisitor visited him. Poprishchin hid “under a chair,” and his visitor calls him by multiple names including King Ferdinand, to get him to come out. Eventually, the inquisitor finds him, and chases him with a stick.
The “grand inquisitor,” who is really a staff member at the asylum, is aware of Poprishchin’s specific delusions and taunts him. He calls Poprishchin by the name of his made-up alter ego in an attempt to goad him, and then beats Poprishchin. Poprishchin, whose alienation from society is already complete, seems to be singled out especially for poor treatment.