As much as I love a logic problem, the dynamics of groups are never logical, and trying to figure them out has always been tough for me. There are so many motivations that people have, and on top of that, so many ways that people go about acting on their motivations that the combinations are endless. Add to that that even when you think you have a person within a group figured out, new information can always come to light which wholly changes your perspective.
Personally, I strive to have a “Zoey” attitude – look for the positive in everyone and try to keep in mind that there’s always hidden motivations and things going on behind the scenes that I’m not privy to, and therefor spend very little time accentuating the negative. In actual practice, I’m probably a bit more like Anna, splitting the difference. But every now and then, I know I’m a bit like Jack – snarky, cynical and negative.