Why does the eye surgeon help Anderton

Great sample of the dialog by the way, between Anderton and Dr. Solomon Eddie at IMDB.

While the doctor was describing his experience in prison, his um difficulties in the shower, notice something? Something not in his words, but in his tone. He's dispassionate. He's not angry. I think he actually was reformed. Now he just wants to make a living. He talks as if he's going to mete revenge on Anderton. But never does. He's actually thanking him for turning his life around. I mean, a plastic surgeon who sets his patients on fire for entertainment -- look how far he's come. And he knows it. (This is a better question than I first thought.)

There was also the creepy assistant. Doctor talked at one point as if his assistant saved Anderton, because she had a kind of crush on him. But I don't think that's the real reason the doctor helps Anderton. He's way cynical, to be sure, but he's resigned to a boring life of relatively unremarkable crime. And he's okay with that. So maybe he kinda owes Anderton in the end.

@Shane F. makes an excellent point: the doctor's back-story is a plot device meant to call his trustworthiness [and motives] into question, thereby boosting the suspense about whether he will help or hurt Anderton.

Notice how often this movie tricks you with the good-guy / bad-guy dichotomy. Witwer (Colin Farrell) seems bad but turns out good. Von Sidow seems good but turns out bad. Other characters are more nuanced than pure good or pure evil. This doctor character was just one more bad guy that wasn't all bad.