ROTS Mace/ROTS Obi-Wan/ROTS Anakin vs. ROTS Sidious
Setting: Chancellor's Office
Obi-Wan Kenobi is present on Coruscant when Anakin reports that Palpatine is the Sith Lord. Mace, deciding to trust in Obi-Wan's stabilizing influence on Anakin, decides to take Anakin and Obi-Wan along to attempt to arrest the Sith Lord.
Who wins, and, more importantly, will Sidious have the influence over Anakin necessary to get him to turn on his friends?
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Personally, I'd say that, as far as combat goes, the Jedi would take it easily. Mace Windu alone was capable of handling Sidious, and Sidious also must contend with Obi-Wan and Anakin, currently one of the most brilliantly effective fighting teams in the galaxy. It's almost inevitable that he's going to lose the lightsaber duel.
However, Sidious is a master manipulator, and he knows the right buttons to push to turn Anakin. It can be argued that Obi-Wan could keep Anakin from making the wrong decision. He's clearly sympathetic to his former padawan's plight; it'd be virtually impossible to watch how Anakin acts in Padme's presence and *not* tell that they're married/in love, particularly when he's known and trained and basically fathered Anakin for over ten years. But regardless, it would be close even then.
Obi-Wan, regardless of his lightsaber abilities (which are formidable), has shown a latent weakness against Force attacks. Count Dooku knocked him out of the fight in the beginning of the movie with a combination of Force attacks, so unless the other two Jedi can protect Obi-Wan against Sidious' force powers extra-well, I see no reason why Sidious couldn't do the same. If Obi-Wan is knocked out, Anakin will be much more likely to turn to the Dark Side.
So in the end, it depends on if Obi-Wan Kenobi is down for the count or not when Palpatine begins his psychological warfare, and furthermore, it depends on how much influence Obi-Wan wields on Anakin, at that moment in his life, over that situation. Obi-Wan must be able to convince Anakin that Padmé will be safe, very likely while Palpatine attempts to tell Anakin the opposite.
I think that, if he chose the right words, and reinforced Anakin properly mental-wise during the fight, Obi-Wan could keep Anakin from turning. Additionally, we have seen both Mace Windu and Anakin weather Palpatine's force attacks; I think that, with both of them and Obi-Wan himself trying to ensure that Obi-Wan isn't kicked out, they could prevent him from being defeated, and thus unavailable when it matters.
In the end, I think that the Jedi win, and Anakin fulfills his true destiny, but it's hard to tell.
Thoughts?