smeagol

It's the bitter irony of the book -- I think Smeagol *was* changing, but Sam never let him. Frodo was willing to give Smeagol the chance he needed to become a new person and redeem himself, but Sam was so deeply suspicious of him that Smeagol ended up falling back on established patterns of behavior.

In the last chapter or so before the book ended, Smeagol was all set *not* to do what he did, because he was moved with compassion for Frodo. But what does Sam do? He wakes up and says, "Where have you been sneaking off to?" and immediately the light dies out in Smeagol's eyes.

It's no surprise the old fellow attacked Sam personally.