Guild Wars 2

I’m not sure what triggers it, but friendly NPCs within the camp will just start fighting each other randomly. I’ve seen Vigil and Whisper members fight, Whisper agents attacking Priory researchers (who sometimes stay in out of combat mode and just ignore the hits), and even the marmox gets in on it sometimes.

If I remember correctly this is shortly after the Pact is formed/ proposed in the personal Story part.
This out in the world is a camp that is set up by the new Pact members and as yet they do not trust each-other.
It is part of a heart there that you get to talk to them and put their fears to rest.

True, but these fights rarely happen and there is no way to break it up (they still count as friendly to you, and so you can’t make them stop or anything) There doesn’t seem to be any specific trigger for it, they’ll just start fighting all of a sudden, and it doesn’t stop until one dies. So, it seems to be either a bug or just another little thing that’s different from the norm, because you can really affect it.