Simmelian Ties
the friend you'd take a bullet for is usually one you share a third friend with
Grounded in the research on Georg Simmel via David Krackhardt, 'The Ties That Torture: Simmelian Tie Analysis in Organizations' (1999)
the setup
A Simmelian tie isn't just you and one other person. It's a tie where you're both also tightly bonded to the same third party. You + your boy + the boy you both ride for. That triangle makes the connection between any two of you way stronger than a one-on-one link ever would be. The third person is the glue you don't notice until they're gone.
the science
Georg Simmel argued in the early 1900s that adding a third person fundamentally changes a relationship, not just adds to it. Network scientist David Krackhardt formalized it in 1999: a tie is 'Simmelian' when both people are reciprocally and strongly tied to at least one shared other. His finding, blunt title and all ('The Ties That Torture'): these ties are stickier, more binding, and harder to break than ordinary dyads.