Batman Forever is the prequel to the Dark Knight. It follows the adventures of the Joker before he gets these scars.
Joker decides to play some jokes on Batman, so he teams up with Two Face. They rob the circus and Robin's family dies. Batman decides to teach Robin how to be a Batman and they are in cahoots together. So then they fight Joker and Two Face. Seal sings that he compares them to a kiss from a rose on the grey. Alicia Silverstone is also there, if you remember her.
Batman - Christopher Nolan
Robin - Neil O'Donnell
Batwoman - Alicia Silverstone
Joker - John Carrey
Two Face - Tommy Li Jones
Penguin - Joe Pesci
Riddler - Heath Ledger
Mr Freeze - Arnold Schwarzenegger
Poison Ivy - The Bride
Commissoner Gordon - Ben Gordon
"Riddle me this: how did I get these scars" - Joker
"Its the scar. Chicks dig the scar" - Joker