The spawn of the Venom symbiote then attached itself to Kasady through his bloodstream. Carnage achieves this by entering Kasady's body through a cut on his hand. This is the reason why Carnage appears as the colour red, as he entered through the bloodstream, which is of course red.
It could be that in the universe of the Venom movies, this type of strong bond is already known among the symbiotes to result in stronger specimens. This could explain why Venom is so fearful of facing an enemy with a ruddy hue.
Originating as an offspring of Venom, Carnage is much more powerful than its parent symbiote because of the symbiotes' biology, and is in many ways a darker version of him.
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 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.
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.
That way if Eddie gets hurt or something Venom can essentially heal Eddie's injures faster. The reason Carnage is red is because he bonded with Cletus' blood directly just like how it happened in the comics.
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 Venom/Spider-Man feud began years ago due to bad journalism, Spider-Man's heroism, and the mutual hatred of one angry symbiote. Though the Lethal Protector has become an anti-hero since the '90s, Venom is still widely regarded as one of Spider-Man's most well-known and iconic villains.
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.
While Eddie Brock's Venom may not be the strongest here, he is recognizable and the most resilient Symbiote compared to many others. Even though he started out as a pure villain, Brock's Venom showed many heroic traits.
Dylan Brock is the son of Eddie Brock and Anne Weying. When Anne bonded to the Venom symbiote, she somehow became pregnant with Dylan.
Blue Symbiote (2) (Agony): In the comics Agony was one of the symbiotes forcibly spawned from Venom alongside several others by the Life Foundation.
True to his appearance in Marvel Comics, Carnage has the look of a red, Venom-like creature. Carnage aka Cletus Kasady has long been known as one Marvel's most evil villains.
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.
They explain Eddie's deep desire to protect innocents and Kassidy's (psychotic) belief that he is freeing people when kills them. Their fundamental beliefs clash and the parent/offspring relationship between their symbiotes amplifies the animosity.
When it comes to physical strength and abilities, Tom Hardy's Venom is more powerful than Tom Holland's Spider-Man. Venom doesn't need a suit to gain his powers. He can morph his body and grow his mass without any tech or outside upgrades.
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.”
However, just before this, venom tells Eddie that symbiotes have a hive mind that spans “universes”. The reason why venom reacts so viscerally to seeing Peter Parker/Spider-Man on tv? Just like the NWH villains: Venom remembers Spider-Man killing him. That's why he goes “ohhhhh…that guy” and licks the screen.
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.
Toxin is the offspring of the Carnage symbiote, which would make it Venom's grandson, if symbiotes abided by human genealogy. Carnage learns about symbiote reproduction from Venom, but then Carnage flees, wanting to kill his offspring before it bonds and matures.
Carnage is Venom's “Son”
The klyntar is an asexual species, and at some point in their lives, they spontaneously reproduce. This is what happened during the rescue of Eddie Brock.
Carnage is red because the symbiote bonded with Cletus Kasady's blood.
The movie doesn't clearly state why, but Venom is probably afraid of Carnage because Carnage doesn't have the moral restrictions that Venom does. They are alien symbiotes. This means they need another living host to bond with if they're going to survive long-term.