"I don't know the proper way to break a blood pact, but if three people attack each other simultaneously, it can shatter. It's best if two of them are blood relatives; then the blood pact will malfunction and ultimately break."
Severus said calmly, "Assuming Aberforth is not dead, Albus Dumbledore happens to have a biological brother."
Severus stood up and walked toward the door. Vinda made a move to stop him, but Grindelwald raised a hand to halt her.
Chapter 241