imo:
Power moves. Setting up a visible alliance is one - it sets the alliance members up as targets and gives voting block power. Also, orchestrating 'an ouster' is a power move.

Parv - allied with James and Amanda with Oz - they became targets. Jonathan wanted to target Parv early as she was visible. Parv also setup another alliance with Nat/Al, but it wasn't quite so
visible. She became a holder of more power as sensed rather than understood by some of the other players. I don't think that Ozzy understood this. She of course had another quiet alliance with Amanda/Cirie. She is credited with outing Ozzy by Probst and Ozzy himself - I think that they would know better than anybody. (Yes, she was more trusted and therefore it hit worse from her than Cirie).

Amanda - has the one alliance with Ozzy and made some decisions as to who to 'out'. When Tracy put her foot down that she wanted to target Joel, Cirie knew to go to Amanda/Ozzy. I think that Ozzy felt he was the decision maker out of that alliance with Amanda though. Amanda, like Cirie has been part of the several behind the scenes moves. That's all I've seen from Amanda. I'd like to see her swimming around to get the Idol. seems like it takes an reasonable swimmer to find it - Kathy or Ami or Chet (I forget all the people out there that somehow couldn't get it and Ozzy comes out - no problem) couldn't do it