The red hue and unstable, fluid-like design of the character is meant to represent its fusion with Kasady's blood. This strange connection to the color red and its association with blood goes well beyond Carnage's origins.
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.
The reason Carnage is red is because he bonded with Cletus' blood directly just like how it happened in the comics. It was slightly altered in the movie from the comics because of course.
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.
In some continuities, red symbiotes usually means being more aggressive and powerful.
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.
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.
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.
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.
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.
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.
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.
Inside is the Venom-X weapon, which is a type of sticky grenade launcher.
In the comics — and the 2021 movie — it's pretty clearly established that on a baseline level, Carnage is indisputably more powerful than Venom.
They rapidly age the symbiotes and pair them to people: Scream (yellow, female), Agony (pink, female), Lasher (green, male), Riot (grey, male) and Phage (orange, male).
The first and most well-known symbiote is Venom, who originally attached itself to Spider-Man during the 1985 Secret Wars miniseries. After Spider-Man rejected it upon discovering its true evil nature, the symbiote bonded with his rival, Eddie Brock, with whom it first became Venom.
The Lasher Symbiote (of Earth-616) is a green Symbiote that was spawned from the Venom Symbiote by the Life Foundation.
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.
Knull, also known as the God of the Symbiotes, is one of the overarching antagonists in the Marvel Comics universe, serving as the main antagonist of the Venom comic book series.
Besides communicating the apparent fact that Venom wants to eat brains — and Peter's looks tasty to Venom — Venom's hunger appears to be proof of an intrinsic attraction to Peter Parker. Now, it's critical to point out that this has never been a real thing in the comics.
Some people are completely immune to his Spider-Sense. Venom is known to act without setting off his Spider-Sense. This is because the symbiote acquired all knowledge of Peter's Spider-Sense and adapted to combat it. This immunity extended to Venom's "son" Carnage.
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.”