the good turns bad and the bad turns good

Looking for dramas where the initial good/bad status of the lead characters  reverse as the plot goes along.

Thanks :)

I really enjoy the good turn evil troop a lot, here are some of the dramas I absolutely adored with this troop:

Burning Ice - personally I think this has one of the best character developments you will find in asian dramas.
Nobody Knows 
Watcher
Trinity of Shadows  - this is really really good in regards to this specific troop
Victim's Game
The Bad Kids

Of course there are also the very famous ones:
Penthouse - basically all characters either go from good to bad or from bad to good
World of the Married - good to bad. to worse.

I'd say Romance of the Tiger and Rose applies, she starts out as a minor villain character and her second sister is the heroine, which flips as the story goes on