text: The boy also dresses like William, walks like him, but can only speak in a whisper. He begins to give advice to William of an unspecified nature, which he refuses to obey, resenting the boy's "arrogance". One night he steals into the other William's bedroom and recoils in horror at the boy's face—which now resembles his own. William then immediately leaves the academy and, in the same week, the other boy follows suit.
  William eventually attends Eton and University of Oxford, gradually becoming more debauched and performing what he terms "mischief". For example, he steals from a man by cheating at cards. The other William appears, his face covered, and whispers a few words sufficient to alert others to William's behavior, and then leaves with no others seeing his face. William is haunted by his double in subsequent years, who thwarts plans described by William as driven by ambition, anger and lust. In his latest caper, he attempts to seduce a married noblewoman at Carnival in Rome, but the other William stops him. The enraged protagonist drags his "unresisting" double—who wears identical clothes— into an antechamber, and, after a brief sword fight in which the double participates only reluctantly, stabs him fatally.