Regarding the actor == he's great. i am surprised he hasn't been tapped to play Nixon!
Regarding the writing of the character....i think he's always been an opportunist. However, when he was first portrayed, he seemed more on the riding-on-others-abilities rather than evil-mastermind type. Again, a similar comparison with Dana Walsh.
And many other characters have been twisted to suit the plot. Tony Almeida is one...or Curtis -- framed as the next Jack Bauer, but gets killed because he has a sudden urge to seek revenge.
Only Chloe and Aaron Pierce (where is he???? Manny Coto, being a man who understands Trekker's obession with continuity, should know how Aaron has been in every
season of 24!) have seemed to have consistent characterization.