Anakin Skywalker's turn to the dark side.
Walter White's transformation from a harmless high school teacher to a ruthless, murderous drug kingpin.
The Wesley character from the movie Wanted going from being a miserable drone of a human being to a remorseless killing machine who gets enjoyment from being an assasin.
What is the appeal of watching a good guy turn into a bad guy?
An unremarked aspect of Star Wars is how the the Force is in a way an invisible character, the one who keeps the Imperial Storm troopers from blasting Luke (and Leia, too, I suppose,) in the first movie, for example. A key part of Anakin's turn is how the Dark Side of the Force takes over once he has broken self-discipline. After that, he is a different person, one who could kill children. That contamination of his previous personality was not really on screen (and really, how could it be?) But, the slaughter of the children was actually very unpleasant. Worse, it doesn't relate to people because there is no Force. The metaphor or personification or whatever "The Force" is, therefore has no power, no shock of recognition. Also, in dramatic terms,
not seeing the Force makes the story something like Hamlet without the Prince. Naturally, it's less engaging.
The criticisms of Anakin Skywalker as a whiny, spoiled brat presume that evil is at the least a tragedy, where a noble person's flaw leads to an inevitable downfall. Or, even worse, it presumes there is something sexy or cool about being bad. Anakin isn't sexy or cool. He's not captain of his soul and master of his fate but a manipulated stooge. Which is incidentally an artistic necessity if there is to be some innate good left to be restored by Luke at the end of the story.
The prequels seem to me to be pretty accurate about people who fall into doing evil, which is that it isn't because they're sexy or cool or their nobility is tragically undone by a single flaw. It's because they're petty and keep making excuses and change themselves by their actions into something they wouldn't have consciously chosen. They are all, on one level at least, fools. In short, the "pleasure" of Anakin going bad is mixed.
As for Wesley, there is no pleasure. In the movie's degenerate morality, Wesley is not a villain when he's doing the assassinations according to the mystical plan, and when he finds out he's being manipulated, he turns on his masters. In truth, the assassinations are murders and the mystical necessity merely asserted, unbelievably I might add. But Wanted is very much about badassness being sexy and cool. This is silly, which is why good performances and competent camera work and good production end up being worthless.
Walter White's descent is not pleasant like a Sunday drive. It is intense like a roller coaster ride. Walter is going to die of cancer (writing it out permanently instead of giving him a remission would severely undercut the story.) The question is, what kind of life would he have led?
Walter decided that material success, and power, were the most important parts of his legacy. But even if he were to become the new Gus Fring before he died, his legacy would merely be money and blood. The years he spent as a self-despising teacher with health insurance for a sick son were his real triumph, not a romantic victory over enemies, but over self-interest and drudgery and time. He was once a successful father, but now he's led his surrogate son Jesse into murder. Could there be any greater failure as a father?
The reason we care is because fundamentally this is very much like real life, it's just amped up. Beneath all the superficial melodrama, we recognize something of ourselves and our lives. Walter's choice to put money (that he couldn't even spend!) above everything else is a temptation thrust upon us all. Poverty is never too poor to buy unhappiness, and we know it. We too wonder what kind of life we'll have led, what legacy we'll leave, if any.
