Dumbledore left a letter on the Dursley’s doorstep with baby Harry. In it he explained that her sister Lily had died, and if she accepted Harry into her home, she would seal the magical bond of blood between them. Her nephew would be safe on Privet Drive until he turned 17. Although resentful, Petunia accepted Harry as part of the family, although she always favored her own son, Dudley.
Petunia gets her first letter from Dumbledore
Date November 2, 1981
Location in Canon PS1
Type of Event Array