The twisted symbiotes in the universe? Nothing good.
In the serial killer Cletus Kasady manages to escape from the Ravencroft Institute and goes on a murder spree. When Spider-Man tries to stop him, he's assisted by the Silver Surfer, who tells the webslinger he's dealt with symbiotes before and they're among the most dangerous aliens in the galaxy. After the symbiote suddenly splits from Casady, he informs Spider-Man the symbiotes wants to attach to the Surfer and get revenge on the cosmic being. After Surfer chases the symbiote, it does the unthinkable, and bonds with him.
Amazing Spider-Man #431 (1998) opens up with the Carnage Cosmic fighting an internal battle with the symbiote. The Carnage-ized Silver Surfer nearly kills innocent bystanders when he zooms through a building to get into space. While in the stars, the symbiote fights with Surfer to infect his mind - showing him images of Kasady's messed-up childhood which included animal torture, abusive parents, and his rise as a killer.
Silver Surfer's mind manages to see empathy and comion over corruption and chaos. Still bonded with the symbiote, he returns to Earth. After Spider-Man tries to take him down, Surfer reveals he intends on returning the symbiote back to Kasady, who will die without it. Surfer offers a reluctant Spidey a choice, would he rather have Kasady, a human, host the deadly alien being or would he rather have a cosmic being host it? Spider-Man relents and lets him go to a dying Kasady. Surfer lets the symbiote return to Carnage, but in encases him "an unbreakable shell of ethereal energy."
While it would never be explained how Carnage escaped the hold of the Silver Surfer's energy, the Earth is lucky to have the cosmic being on their side. His empathy and comion allowed him to fight off the symbiote bond and return it to Kasady. If Surfer had stayed with the Carnage symbiote, he'd be one of the most powerful Marvel villains ever. He would be Carnage but with the power cosmic - and would be unstoppably powerful. Thankfully, Silver Surfer managed to fight off the madness and in the end and stopped the symbiote from causing further destruction.
