The Carnage symbiote has always been a black sheep amongst its kind. Possessing an innate lust for violence and destruction that surpassed even the most vicious of their kin, Carnage has become one of the most feared entities in the Marvel Universe. Even other symbiotes are terrified of their crimson sibling's capacity for cruelty. Unfortunately, the deadly divide between Carnage and the rest of their kind has only gotten worse in the aftermath of the King in Black event, with saw Knull, the King in Black, killed and usurped by Carnage's long-time enemy Eddie Brock.
While the rest of their species despised Knull and renounced their malevolent ways in the wake of his death, Carnage has doubled down on their sadistic tendencies and undergone a terrifying transformation. The creature has transcended the symbiotes' traditional need to claim a host. In doing so, it's become an independent entity with powers that far exceed those of a normal symbiote. While it's unclear where this evolution will ultimately take Carnage, their newfound abilities are eerily similar to Knull's, and their desire to avenge the fallen god of the symbiotes could lead to them becoming a cosmic being on par with the Lord of the Abyss.
Upon learning of Knull and his all-consuming desire to exterminate all life in the universe after fusing with a fragment of the Grendal symbiote dragon, Carnage developed a fanatical fixation with the diety and dedicated their existence to freeing Knull from his imprisonment. Although nearly destroyed by Eddie and the Avengers and forced to bond with a great white shark, Carnage succeeded in freeing Knull. The supposed King of Black then quickly made his way to Earth with an army of subjugated symbiotes. Forced to remain in hiding for the majority of Knull's invasion to regain their strength, Carnage finally joined the attack in Carnage: Black, White, and Blood #2, "Carnage Shark" (by Donny Cates, Kyle Hotz, Rachelle Rosenberg, and VC's Joe Sabino) at the exact moment an Enigma Force-empowered Eddie killed Knull. Outraged by the death of their god, Carnage swore revenge but was almost immediately mobbed by a legion of vengeful symbiotes and torn to shreds.
Carnage survived the encounter. However, its prolonged separation from long-time host Cletus Kasady and communion with Knull had a profound effect. It developed the ability to exert its will over other symbiotes and maintain a humanoid form without a host. Throughout Philip Kennedy Johnson's Extreme Carnage series, Carnage explored the limits of their new abilities, creating a new hive of loyal symbiotes and absorbing Iron Man's Extrembiote Armor to become even more powerful. Eventually, in Carnage Forever #1's "Unmade in His Image" (by Ram V, Salvador Larroca, Rain Beredo, and Sabino), it kidnapped long-time Spider-Man villain Hydro-Man. The plan is to absorb the b-list antagonist's hydrokinetic powers to evolve further.
When discussing their motives with their deranged "fan" Kenneth Neely in Carnage #1's "In the Court of Crimson" (by V. Francesco Manna, Dijjo Lima, and Sabino), Carnage admits that they wish to escape the "obsessions" that motivated them throughout their relationship with Cletus. Only then can they perhaps finally discover their purpose in life. Although this might not sound inherently malicious, their actions give the game away. For instance, they share this with Kenneth while torturing a captive Hydro-Man. That suggests Carnage is unlikely at best to be entering a kinder, gentler phase. Considering how interested Carnage seems to be in expanding the limits of their power, their new goal could be to overthrow Eddie and become the new god of the symbiotes.
Carnage already held a deep disdain for Eddie long before he killed Knull. Unfortunately, Brock's role in destroying the former King in Black has painted a massive target on Eddie's back. With its unique ability to control other Symbiotes, Carnage creates a unique threat to Eddie, who is already suffering from the strain of maintaining the symbiote hivemind. Having developed a close relationship with Knull, Carnage has emulated their fallen master in many ways, including incorporating the Lord of the Abyss's spiral symbol into themselves as a show of dedication. Carnage has already made it clear that they disapprove of Eddie taking Knull's throne. Their grandiose speech about finding their purpose almost comes off as a rehearsal for the role that they plan to claim from their "father's" host.
If Carnage does succeed in claiming Eddie's title, then the Marvel Universe could bear witness to the birth of a new dark god. The matter is only further complicated by the mysterious Meridius's designs on the role as well. Carnage's challenge to the throne could plunge the Earth into a second symbiote war, with the fate of both humanity and symbiote kind hanging in the balance.