Please note, the image above is the result of my fan edit/manipulation which is my attempt at making the image have a different look and feel to the original. The original work can be found in the link below.
Cletus Kasady is a psychopath and a homicidal sadist. Kasady is a deeply disturbed individual with a dark past: as a child, he killed his grandmother by pushing her down a flight of stairs, tried to murder his mother by tossing a television into her bathtub, and tortured and killed his mother's dog. After the latter, his mother then tried to kill Cletus, and was apparently beaten to the brink of death by Kasady's father, who received no defense from Kasady during his trial. As an orphan, Kasady was sent to the St. Estes Home for Boys, where his antisocial behavior made him the target of abuse from both the other orphans and the staff. Kasady gained revenge by murdering the disciplinarian administrator, pushing a girl (who laughed at him for asking her to date him) in front of a moving bus, and burning down the orphanage. It was during his brutal years at St. Estes that Kasady acquired his philosophy that life was essentially meaningless and futile, that "laws are only words", and came to see the spreading of chaos through random, unpatterned bloodshed as "the ultimate freedom."
Kasady became a serial killer. He was then captured and sent to Ryker's Island prison for 11 murders—though he bragged of a dozen more—where he shared a cell with Eddie Brock, who had lost the alien symbiote that transformed him into the supervillain Venom. Brock's symbiote soon returned and bonded with him again, and unwittingly left behind the symbiote's offspring. The new symbiote then entered Kasady's bloodstream through a cut and bonded with his blood, transforming him into Carnage. He escaped prison, and began a series of murders, and at the scene of each crime, wrote "Carnage" on the walls with his own blood. He was found by Spider-Man, though the hero proved to be no match for Carnage's powers. In desperation, Spider-Man made a truce with Venom to fight Carnage. Carnage was defeated with sonic weaponry, but the symbiote lived on because it is merged with Kasady's bloodstream.