Also was the other person really unfriendly or detrimental to the group or was it somehow subjective/ego driven (threatened by a newcomer) ?
Ego driven? Certainly. I don't think there was any fear of newcomers, but was more about loyalty.
Many of these people had worked together previously, and would coordinate to enforce what they wanted. Eventually they moved in mass to another company, killing our eng department. They rinsed and repeated at the new company.
I had an HR rep tell me they felt like there was little they could do, because of their culture of silence, and how profitable they were.
How do we know our critics are unjustified unless we can feel free to word them out ? To me the issue was the bad reflex for people to speak in the back to put it simply. And not to blame Jessica, there's also the natural reflex to feel stuck in shock when facing people who clearly are not speaking their minds. In that case I'm sure a little habit of "what." to those people can quickly stop the toxic game.
That's why I thought it requires most people to be a bit tougher and yet softer and have a natural or trained desire to confront things. It's a strange game of having empathy about our weaknesses and yet not letting them spoil the place.