In Venom: The Last Dance, it's revealed that when Venom saved Eddie Brock's life in 2018's Venom, a Codex was created that solidified their bond. That's reawakened Knull on Klyntar and the King in Black sends his Xenophage to retrieve the key that can free him from his prison.
This is a big change from the comics but one that may have major implications for Venom on screen moving forward.
On the page, a Codex refers to the trace amounts of a Symbiote left in a former host's body. That connects to the Symbiote Hive-Mind which preserves the consciousnesses of hosts, creating an afterlife of sorts. It also doubles as an afterlife for deceased symbiotes, something we see in Venom: The Last Dance when Carnage and Riot are shown seemingly frozen in place.
This has led to Cletus Kasady's Codex, for example, being able to pilot the reborn Carnage Symbiote following his death. It's complicated and the Sony threequel definitely simplifies the concept.
As for what this means moving forward, it likely opens the door to fallen Symbiotes being brought back from the dead (meaning we may not have seen the last of Carnage, even if Cletus Kasady's physical body is no more).
Eddie and Venom being the only ones with a Codex - and yes, it features the same swirling pattern from the comic books - is surely a plot point that will be revisited down the line. However, what we can't figure out is what, if anything, this will mean for Spider-Man 4 if and when Venom crosses paths with Peter Parker.
Back to the Venom franchise, though, and when the leads do inevitably reunite, the fact they're the only Codex in the universe is surely going to be revised.
Regardless of whether the Codex concept is a one-off, making it a major plot point in Venom: The Last Dance deepened Eddie and Venom's bond in a way that pays homage to the source material. We also get an exploration of the Symbiote mythology that previous movies have largely ignored.
"The most cinematic, monumental Venom movie to date, we said in our recent review of the movie, "The Last Dance leaves room for improvement but by upping the stakes and allowing Eddie and Venom to bond, it’s epic and heartfelt enough to leave us hoping this is far from Tom Hardy’s last whirl as the Lethal Protector."
In Venom: The Last Dance, Tom Hardy returns as Venom, one of Marvel's greatest and most complex characters, for the final film in the trilogy. Eddie and Venom are on the run. Hunted by both of their worlds and with the net closing in, the duo are forced into a devastating decision that will bring the curtains down on Venom and Eddie's last dance.
The movie stars Tom Hardy, Chiwetel Ejiofor, Juno Temple, Peggy Lu, Alanna Ubach, Stephen Graham, and Rhys Ifans. Kelly Marcel directs from a screenplay she wrote, based on a story by Hardy and Marcel. The film is produced by Avi Arad, Matt Tolmach, Amy Pascal, Kelly Marcel, Tom Hardy and Hutch Parker.
Venom: The Last Dance will be released in theaters on October 25.