Remember how Stella was sure Cobb had something on Paden, that was preventing Paden from acting basically... I was kind of expecting an answer at the end, after Paden wins the fight. Anyone?
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"Oh I'm sorry, did i break your concentration?" - Jules, Pulp Fiction
Cobb was using Paden's friendship with Stella as his bargaining chip.
At the end of the house fire scene, Cobb blatently threatens Stella while he's talking to Paden. Cobb says that he might need to "make an adjustment" if Paden gets involved and then says that he's referring to Stella. Paden then asks Cobb what Stella has to do with it and Cobb's chilling answer is "nothing at all".
Also, when Stella and Paden are sharing a drink in the saloon after the house fire, she figures out that Cobb is using her to get to Paden. She then tells Paden that she hates to be used to hurt innocent people. This it what Paden is kind of waiting for - the go ahead to get involved.