This isn't a complaint - more of an observation/question... do the Sith know about the Rule of Two? I would assume they do. Which would, I would think, have them constantly on guard whenever a potential Sith #3 pops up, since there ain't gonna be three for long, one way or another! Given that, I always assumed that Dooku went along with plans to turn Anakin figuring that when the time came, he would defeat Anakin (and Sidious would retain HIM as his apprentice). When Vader fought Luke in ROTJ, I got a much greater sense of resignation there - Vader was going to lose, either way (he seemed to feel more like a slave than an ally by that point). So why didn't Dooku blurt out the truth once defeated? No easy answers,but I thought it was a combination of things... a hope that at the last moment Anakin would "regain his senses" and/or his Master would back off, a fear that saying something might lead to rash action (oops), etc.