När Sirius skulle bli hemlig målare, övertygade han dem i sista stund för att byta till Peter.
He was pointing at Black, who shook his head slowly; the sunken eyes were suddenly overbright. “Harry . . . I as good as killed them,” he croaked. “I persuaded Lily and James to change to Peter at the last moment, persuaded them to use him as Secret-Keeper instead of me. . . . I’m to blame, I know it. . . . The night they died, I’d arranged to check on Peter, make sure he was still safe, but when I arrived at his hiding place, he’d gone. Yet there was no sign of a struggle. It didn’t feel right. I was scared. I set out for your parents’ house straight away. And when I saw their house, destroyed, and their bodies . . . I realized what Peter must’ve done . . . what I’d done. . . .”
Harry Potter and the Prisoner of Azkaban, Chapter 19
Detta gjordes av Sirius i tron att bluffen Voldemort och hans anhängare skulle komma efter Sirius var ett bättre alternativ, utan att veta att Peter redan hade sålt ut till Voldemort.
“Lily and James only made you Secret-Keeper because I suggested it,” Black hissed, so venomously that Pettigrew took a step backward. “I thought it was the perfect plan . . . a bluff. . . . Voldemort would be sure to come after me, would never dream they’d use a weak, talentless thing like you. . . . It must have been the finest moment of your miserable life, telling Voldemort you could hand him the Potters.”
Harry Potter and the Prisoner of Azkaban, Chapter 19
Så i princip var de enda som visste de som var där. Petrus förrådde Potters till Voldemort, och han lyckades flykten strax efter att Potters dödades när Sirius kom för honom. Därefter var Sirius på väg och trodde att han var ansvarig, och den enda som förstod honom var tydligen död.
“Just before he transformed,” said Black. “When I cornered him, he yelled for the whole street to hear that I’d betrayed Lily and James. Then, before I could curse him, he blew apart the street with the wand behind his back, killed everyone within twenty feet of himself — and sped down into the sewer with the other rats. . . ."
Harry Potter and the Prisoner of Azkaban, Chapter 19