villain vs. villain, or bad guy turns good and helps main lead

I find it amusing when bad guys start going after each other lol

sort of like in Let Me Introduce her Detective Kim wanted to chase after Ms Jung in the later eps, the one who hired him to kill the FL but ends up helping ML in the end 

or Mistress  Young Dae kills the hair stylist woman, and that final showdown in the abandoned building

The Last Empress is exactly what I'm looking for LOL I love makjangs/melodramas!