Chase sold out House in S1 and was a suck-up for the first three seasons, now they've gone to great lengths to show that he's Loyal and Noble and Strong. In short, he changed. If people really don't change, David Shore, then Chase would still be a weasel and a suck-up. Cameron also changed during the course of the show, becoming less naive and more tough and independent. For a while she did so without being cynical, which I appreciated a lot, but they had to have her change that way too.