Scratchy is the titular main protagonist in The Itchy and Scratchy Show, a parody of Tom and Jerry that play in The Simpsons world. He parodies of the character Tom from Tom and Jerry and his role as victim. Scratchy is relentlessly persecuted by the sadistic Itchy (although they are ironically good friends in real life).
Whilst the very earliest Simpsons episode depicted Scratchy as also trying to kill Itchy, the series quickly established Scratchy as a friendly and humble character who seeks to live peacefully and help others. He is usually depicted as unknowing of Itchy's attempts to murder him. On several occasions, Scratchy is shown helping out or even attempting to rescue Itchy, only to be betrayed and killed by the sociopathic rodent.
Some good examples of Scratchy's heroic nature include the cartoon, "Cat Splat Fever", where Scratchy tries to rescue Itchy from a well only to be killed by the evil mouse. A good example of Scratchy's kind nature is in the cartoon the "Brawl of China" wherein Scratchy spares Itchy after defeating him in combat, despite Itchy being a cruel warlord who murdered defenseless Scratchy's father in cold blood, though sadly Scratchy's mercy is repaid by Warlord Itchy backstabbing and killing the kind hearted hero.
Even in the few times when both Itchy and Scratchy are fighting, Scratchy is established as being on the defensive and in the right. In a cartoon where Itchy and Scratchy are leading armies against each other, Scratchy cries "for freedom" in contrast to Itchy's "for tyranny" warcry.
Scratchy is shown in several cartoons to have a family of his own, usually consisting of his wife and son, though occasionally other relatives like his parents and apparent daughter have appeared. Tragically the evil Itchy has no compunctions with killing Scratchy's family, even the children.
In The Simpsons Movie, a movie of Itchy & Scratchy is being played, where both Itchy and Scratchy are astronauts who reached the moon. While Scratchy says that he comes in peace for cats and mice everywhere, Itchy suddenly impales him with his flag pole several times, then whacks him with the pole and once Scratchy is down, Itchy cracks Scratchy's helmet, taking away his oxygen and leaves him on the moon to die. When he goes back to Earth, he lies to the public that he did everything to rescue Scratchy although he actually did the opposite, and he ends up becoming president of the USA. While looking into the moon with a telescope, he sees that Scratchy is still alive and willing to tell everyone the truth. Itchy then shoots a salvo of rockets towards the moon to kill Scratchy, succeeding at this murder.