There are three powerful entities, each one of them having a strong link to their universe.
The first one represents the magical Disney Universe of Mickey Mouse. This Universe contains all the cartoons owned by Disney, including companies such as Marvel.
The second one represents the earthly WB Universe of Bugs Bunny, the Universe in which are contained all the cartoons owned by WB, including companies such as DC.
The third one represents all the cartoons and characters that aren't linked with the other two. This third entity is unknown, because he won't show himself, like a master of disguise, which will make his appearence when one very great earthquake of events will make the three worlds tremble solemnly.
The first notable cartoon character is Mickey Mouse, the owner of the Universe related to magic. He has transferred his character in it, making the storylines, cartoons, and characters strongly linked to morality. This is the Universe of morality and severe punnishment to anyone who transgress the law.
All were going well for years, this harmony growing stronger and stronger, until something out of order happened. A spirit of great mischief, relatively strong as Mickey, appeared to break the system imposed by him in order to shatter this law into pieces.
And a war started, Mickey Mouse and this strange spirit fighting each other for a long period of time. The outcome of the battle decided the fate of Mickey's world. They ended the battle in a tie, and realising that both were equally strong, the spirit of mischief promised to Mickey he'll spare him of his presence on one condition. That condition represents a dangerous outcome of the war, an outcome from which the great anguish of cartoon history begins. He asked Mickey to transfer half of his character in this world, so that his subjects experience not only fairness, but the opposite of it as well. Mickey Mouse accepted it. He began the process of transfering some of the traits of his visitor.
One moment of unawareness, and this ugly, deceitful spirit stole a third of Mickey's land, inplanting at the same time the seeds of evilness and chaos in the remaining one. This event isn't showing up after a long time of peaceable Universe, the strange meeting between Mickey Mouse and his archenemy being among the first.
As the archenemy of Mickey Mouse left, a great earthquacke took place in the magical world, caused by the lack of a third part of it. After resquing his characters, Mickey Mouse began to fear and blame himself for his unawareness. He thought of the terrible feature regarding all of the characters in the cartoon history. His mischievous archenemy has the power of drawing and redrawing characters and lands. That power isn't perfected until some moment in the future, when he exercises it in a cruel way on one of his relatives.
At first, in his own Universe, he appears with his friends, preventing them from meeting a pig-like character, who was willing to kill them. This is the first meeting of him and one of his characters, in which he exercises his power in a cruel way. The first appearences of him are proving his sadistic nature, his experiments on the innocent being deliberate and unfair. Even if his real name and origin aren't known, his features are clearly rabbit-like, and he is called at first "Happy Rabbit". He rules the earthly side of the Universe, the most horrible and violent of the three. He has proved, by his own action, his disgusting desire and aspiration in turning all of the peaceable places upside-down through fierce and outrageous violence. The seeds thrown by him in Mickey's Universe had proven effective, and the result was none other than the growing of abomination and violence in his world, the Marvel side representing the most noticeable example.
The ugly demon of mockery and injustice sung a song on triumph regarding his achievement (the noticeable lyrics)
All the world was gay. Swinging on its way. Things were looking brighter day by day
Nothing ever wrong
Life was just a song, Till that Looney Tune came along
He was so satisfied by his victory, that he indulged in madness in the second part of the song.
The great affliction was just about to start.