The coloration of symbiotes is actually much more complex than mere appearance. In Marvel lore, red symbiotes are generally stronger than their black counterparts and are usually much more vicious as well.
Venom Confirms Red Symbiotes Are Stronger Than Black
Venom #8 has changed those assumptions, with the immediate implication of a red symbiote other than Carnage also being stronger than Venom confirming there is indeed a hierarchy in place. At the very least, a red symbiote is naturally stronger than a black symbiote.
Marvel Comics' new version of Venom has become the most powerful symbiote ever. Dylan Brock, the son of the original Venom host, Eddie, has unlocked a new power that allows him to sever a symbiote's connection to the hive mind, which makes him a threat even for the all-powerful Kings in Black.
This stronger bonding with Kasady resulted in Carnage being more physically formidable than Venom was. This joining together through the blood is also the explanation for Carnage's red color scheme.
Marvel's Spider-Man 2 New Riot & Venom Go To School To Deal With Sandman, What If? Full Battle
Why is Carnage red instead of black?
In fact, right after its birth, the symbiote proved to be more adaptive than its father Venom, merging with Kasady's blood to forge a more visceral bond with its host. This also gave its “skin” that distinctive red hue. But it didn't stop there—Carnage continued mutating throughout the character's horrible history.
After Venom broke through the prison cell that held his host Eddie Brock, a small piece of the symbiote was left behind. That piece soon bonded with Cletus Kasady, Brock's cellmate. Once he came into contact with it, the two bonded, and Carnage was born.
By eating Carnage, Venom is effectively returning his spawn back to his former "unborn" state within Venom's mass, not taking anything he didn't already have into his cells.
Carnage does have more abilities, but was like a rampaging kid and Venom ate it to kill it. Riot was cunning, and was even able to rip Venom from Brock and would have eaten him if Brock didn't rebond with it.
Perhaps the Marvel Universe's deadliest symbiote, Carnage debuted in AMAZING SPIDER-MAN (1963) #345. Shortly after spawning from Venom, the Carnage symbiote bonded to a serial killer named Cletus Kasady.
Taking control of him, the symbiote fed off his life force until it encountered the Hulk mid-battle with Doctor Strange and the Avengers. Sensing his power, the symbiote abandoned Peter for the Hulk -- gaining control of the Hulk while leaving a withered and aged Spider-Man on the verge of death.
According to symbiote biology it would be The All-Black, also known as The Necrosword. Due to being the first symbiote knull ever made, it's already weak as it is, only granting the basic suit and itself as a weapon.
The Toxin symbiote has a long and troubled history in the Marvel universe as both a villain and an anti-hero. Toxin's place in Venom and Carnage's genetic line and its difficulty with hosts have all helped define the symbiote and its ever-expanding place in the Marvel Universe.
In the movie, Riot was not a child of Venom but was an alien that arrived on Earth at the same time as Venom. Furthermore, Riot was more equipped for battle and proved to be stronger than Venom every step of the way.
In the present, he attempts to use Eddie Brock to investigate Cletus Kasady, but is seemingly killed during a battle between the Venom and Carnage symbiotes and Barrison. However, he absorbs a piece of one of the symbiotes, which later revives him and causes his eyes to glow blue.
Venom came to empathize with Eddie's status as a "loser", eventually deciding to turn on its own kind and save the Earth from being invaded. The symbiote ultimately agreed to work alongside Eddie as a vigilante, to only hurt bad people despite its own confusion of how it can tell the difference of who is good or bad.
Personality. Carnage is a sentient being of pure evil, shown by how moments after the symbiote was born it wreaked havoc in Prison during its escape. Carnage also has a deep hatred for its father, Venom, wanting to kill him so that he could be the only symbiote on the planet and thus unstoppable.
Venom's symbiote has explained on many occasions that the Klyntar planet is practically devoid of emotions, yet over time he knows that he forms genuine love for Eddie. Venom bonds more with Eddie and experiences guilt, jealousy, and sadness over his other half.
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.
Unaware of his true parentage, Dylan met Eddie when he appeared on Carl's doorstep looking for help. Under the belief they were siblings, Dylan asked Eddie to use Venom to kill Carl for his abusive behavior. Around this time, Eddie learned the Venom symbiote had manipulated his memories and realized Dylan was his son.
In spite of Carnage's brutal methods and relentless nature, the symbiote itself was still held back by the same weaknesses to extreme heat, electricity, and sonic weapons that all others of its kind suffered from. More importantly, Carnage was held back for the vast majority of its life by its need for a host.
This shapeshifting allows the symbiote to change its color and texture, which allows it to blend into the environment as a form of camouflage, or to change the host's outward appearance (including mimicking the appearances of other beings). the ability to sense the thoughts and will of the host.
Venom and Carnage have traditionally been enemies, so it's fascinating to discover that in dire circumstances, they would be willing and able to combine as a single symbiote villain and overpower even a strong-willed hero like Miles.
