I'll be honest, I'm not a fan of the Carnage symbiote. While he was a cool character in the comics, the movie ruined him. In the movie, Carnage seemed to have no purpose other than destroying everything around him. That's why it's such a shame that the one scene where Carnage had a plan, which would have allowed us to consider him an intelligent being, was cut. However, I think that his chaotic behavior was due to both his young age, as he was, after all, a “newborn,” and secondly, his host, Cletus Kasady, was an emotionally unstable psychopath, which certainly had an impact on the young symbiote. I think that if Carnage had stayed with Venom and Eddie instead of ending up with Cletus, he would have had a much better chance of becoming someone better.
In my universe Earth666, Carnage also exists, although his story is short and tragic. He was born on the symbiotes' home planet, but he was very weak and sickly. Venom tried to keep him alive, but unfortunately to no avail. In the end, the little one was devoured by his father, which was a huge trauma for Venom. The black symbiote was never able to come to terms with the loss of his offspring and became bitter and aggressive.