The idea that he would become stronger after eating Carnage seems to come from an idea that he would be absorbing Carnage's symbiote powers and properties into himself, therefore becoming stronger. However, unlike the mutant powers of Rogue, Venom is not absorbing Carnage but consuming him.
Carnage barely put up a fight. Pieces of the symbiote were on him, but he didn't fully transform or try to defend himself. Venom simply pulled the symbiote off of him and ate it, becoming stronger.
Venom managed to remove the Carnage symbiote from Kasady's bloodstream to the extent that, despite his best efforts, Carnage would not reemerge from Kasady's body. Though Carnage did not settle inside Venom after being ingested, as Venom would occasionally see Carnage try to reemerge from within his symbiote.
When a symbiote absorbs another symbiote it gains the ability to control the devoured symbiote's matter. That's why riot was larger and was able to grow thorns. He had absorbed several symbiotes by the time venom and riot fought.
Venom EATS Carnage | Final Fight | Venom 2 | CLIP.
The bond between the Carnage symbiote and Kasady was stronger than the bond between Brock and the Venom symbiote. Cletus Kasady was also a serial killer and thought of as insane. As a result, Carnage is far more violent, powerful, and deadly than Venom.
As for the less-likely to return, unfortunately, we can't see a way for Woody Harrelson to return as Cletus Kasady/Carnage, given that the film ended with Venom biting his head off.
Briefly retracting Venom from his face, Eddie apologized to Cletus before Venom angrily devoured the serial killer's head and contemptuously tossed his corpse aside.
The son of Carnage, Toxin, was believed to be the most powerful symbiote ever created. The raw power of Toxin was so great that he was feared even by the King in Black, Knull, creator and leader of the symbiotes.
Blue Symbiote (2) (Agony): In the comics Agony was one of the symbiotes forcibly spawned from Venom alongside several others by the Life Foundation.
Cletus Kasady
The bond between the Carnage symbiote and Kasady was stronger than the bond between Brock and the Venom symbiote. Cletus Kasady was also a serial killer and thought of as insane. As a result, Carnage is far more violent, powerful, and deadly than Venom.
Venom uses the same black goo-like substance that makes up his mass to generate webbing to shoot. As a result, there can be too much of a good thing. If Venom uses too much webbing, it actually pulls from his own body mass, which weakens the symbiote “suit.”
While teaming up with Spider-Man often leads to the Carnage's defeat, Venom doesn't really stand a chance on his own. Carnage was born from Venom's symbiote, and he is simply stronger, faster and more durable than his "father."
His symbiote is corrupted and evolved, making Carnage even stronger than both Venom and Spider-Man.
In the trailer, the Venom symbiote expressed reluctance about fighting him after noticing that Carnage is a “red one,” which suggests that red symbiotes are naturally more powerful than all other members of his species.
While in prison, Venom produces an offspring named Carnage. (He reproduces asexually, in case you were wondering.) Venom doesn't tell Eddie about it, and Venom and Eddie escape prison. Once they're gone, Carnage bonds with Cletus.
The Hybrid Symbiote was considered the strongest of the Venom-spawn created at the Life Foundation. It was created after the Symbiote Scream destroyed the other four Life Foundation creations Phage, Riot, Lasher, and Agony.
Carnage was once a serial killer known as Cletus Kasady, and became Carnage after merging with the offspring of the alien symbiote called Venom during a prison breakout. The symbiote amplified his psychotic nature making him even less mentally stable than he had been previously, and therefore even more dangerous.
The original Carnage symbiote was the first offspring of the Venom symbiote, spawned when it broke Eddie Brock out of prison. The newborn symbiote bonded to serial killer Cletus Kasady, merging with his blood to become nigh-inseparable from him, and Carnage was born.
Likely stemming from his loneliness in prison, Cletus desired Eddie's friendship to make his separation from Shriek (his lover) bearable.
During the last interview with Brock, Kasady started mocking the reporter by wishing him a heartbreak for uncovering his secrets. Venom wasn't satisfied with his actions and attacked the prisoner, which resulted in Cletus bitting Eddie's hand. Right after the bite, Carnage was born and bonded with its host.
Why is Carnage so powerful? The Venom symbiote eventually found Eddie and reunited with him, unknowingly leaving behind its offspring. This offspring eventually bonded to Kasady's blood through a small cut, making the Carnage symbiote have its red appearance, which resulted in Carnage being more powerful than Venom.
During the fight, Mulligan is apparently killed by Barrison, but absorbs a piece of one of the symbiotes, which later revives him and causes his eyes to glow blue.
Venom: Let There Carnage (2021)
Shortly after the events of Venom, Eddie Brock is still in contact with Cletus Kassidy.