Percy frowned, but let it pass. "So, possible spider-related trauma aside ... you think that Quirrell and possibly Snape are trying to steal the Philosopher's Stone, which you think is hidden on the forbidden third-floor corridor behind a Cerberus, and you have deduced this from a number of surprisingly convincing clues." The twins nodded. Percy pinched the bridge of his nose in frustration. "And you have failed to report this to the Headmaster ... why, exactly?"