The Joker is a criminal he is therefore threatened by Yagami he therefore wants to kill him and the Joker is a criminal so the God Of Justice shall strike him down! ....but they most find out who is who first.
THE CASE FOR EVERYBODY'S FAVORITE CLOWN
The name of the Joker is never revealed in the comics
Master at mind games
THE CASE FOR THE GOD OF THE NEW WORLD
The Joker deals with Batman, a man who is not willing to kill.Light....let us just say it is another story.
Can kill without being being there of living any trace
THEY BOTH HATE TO LOSE!!!!!!