"Keep on straight, Remus, you know exactly where we’re going," she replies sharply. "So you see, boys, my problem comes from the fact that Pettigrew, in order to become an illegal animagus, would have had to first find books hidden in the restricted section, then gather the ingredients, manage the meditation, potion, and spellwork, then—if he was successful in all of that—he would have had to undergo the transformation, knowing that if he failed, he could become permanently stuck as partially or fully an animal, or worse."