Peter had been Harry Potter's godfather and a close friend of James Potter and Sirius Black. He betrayed James and Lily Potter to Lord Voldemort, resulting in their deaths. To escape the blame, he cut off his finger and used a powerful spell to transform himself into a rat.
He then lived in hiding for 12 years, posing as Ron's pet rat. This secret was eventually revealed in *Prisoner of Azkaban* when Harry, Hermione, and Ron encountered Sirius Black, who had been falsely accused of killing Peter.
Here's a breakdown of the secret:
* Peter Pettigrew's betrayal: He betrayed the Potters to Voldemort, leading to their deaths.
* His transformation: He cut off his finger and used a powerful spell to transform himself into a rat.
* Hiding in plain sight: He lived as Ron Weasley's pet rat, Scabbers, for 12 years.
* Revelation: His true identity was revealed in *Prisoner of Azkaban*, when Harry, Ron, and Hermione encountered Sirius Black.
The revelation of Peter's true identity was a major plot twist in the series and had significant consequences for the characters. It also highlighted the importance of trust, loyalty, and the power of secrets.