For those who have watched the newly released Fantastic Beasts: The Crimes of Grindelwald, you will find a "bloodpact" (which is something very similar to the Unbreakable Vow) mentioned there between Dumbledore and Grindelwald where they swear to not fight each other ever.

However, we know from the Harry Potter and Deathly Hallows book that Grindelwald and the two Dumbledore brothers had fought which led ultimately to the death of Ariana Dumbledore:

And then ... you know what happened. Reality returned, in the form of my rough, unlettered, and infinitely more admirable brother. I did not want to hear the truths he shouted at me. I did not want to hear that I could not set forth to seek Hallows with a fragile and unstable sister in tow. ‘The argument became a fight. Grindelwald lost control. That which I had always sensed in him, though I pretended not to, now sprang into terrible being. And Ariana ... after all my mother’s care and caution ... lay dead upon the floor.’ (Harry Potter and the Deathly Hallows, Chapter 35, "King's Cross")

Needless to say, this event occurs in 1899, long before 1927, the year Crimes of Grindelwald is set. Now obviously this bloodpact was made between the two before Ariana's death because Grindelwald fled right after her death. So shouldn't have either of the two individuals or even both died for having violated this pact?

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    I think the truth is we don't know the semantics of blood packs yet and if there are catch 22s between blood pacts and/or what truly constitutes a "duel". I have read some speculative ideas that perhaps Albus got in the middle of a duel in progress between Grindelwald and Aberforth and he was able to "block" spells, but because of the pact, it rebounded and accidentally killed his sister. Nov 22, 2018 at 18:52
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    Evidently this will be answered in Fantastic Beasts 3 - link to website and podcast - wizardsandwhatnot.com/2018/12/17/blood-pact-fantastic-beasts-3
    – JohnP
    Sep 10, 2019 at 14:42
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    Also waiting for the answer but it appears that Blood Pact was a little more specific - like not to fight each other or say harm or stop each other. And somewhere I think Grindelwald needed it more than Dumbledore did. When they were fighting with Ariana around, Grindelwald was fighting Aberforth and Dumbledore was trying to block their curses and spells from reaching the other. He might have used some spells himself to defect another spells/curse but in essence he wasnt fighting Grindelwald to stop or harm him but to protect him in a way. Feb 17, 2021 at 19:12
  • @ShrutiJoshi: you could now turn your comment into an answer. It was a very good guess of yours! (how the Bllod Pact works is revealed in Fantastic Beasts: The Secrets of Dumbledore)
    – WoJ
    Apr 27, 2022 at 9:10
  • Any update? Since, now Fantastic Beasts 3 has been released.
    – user31782
    Jul 30, 2022 at 14:26

1 Answer 1


The blood pact was finally broken when Dumbledore and his brother Aberforth shielded Credence Barebone from Grindelwald's Killing Curse, inadvertently violating the terms of the pact, rendering it void. The blood pact fell to the ground and shattered, instantly enabling the two to duel each other.

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