WARNING: The following contains spoilers for Symbiote Spider-Man: King in Black #3 by Peter David, Greg Land, Jay Leisten, Frank D'Armata and VC's Joe Sabino, on sale now.
In the present of the Marvel Universe, Knull has attacked and taken over the entire planet in the King in Black event series. What's more, the god of the symbiotes' power is so great that it has even begun to affect the past. In Symbiote Spider-Man: King in Black #1, Spider-Man and several other heroes witnessed Knull's rise in power in a time period that is meant to take place shortly after the 1984-1985 event series Secret Wars.
Thankfully, the past already had a powerful character who knew all about Knull: Kang the Conqueror. In fact, the time-traveling Avengers villain has been assembling a team to stop Knull. Of course, it's uncharacteristic for the villain to fight to protect the world and in Symbiote Spider-Man: King in Black #3, Kang justifies himself by using the logic of the Marvel Cinematic Universe's Star-Lord when he is questioned by the Web-Slinger.
Kang the Conqueror is a time-traveler who originally hails from the far future. In Symbiote Spider-Man: King in Black #1, it was revealed that, through his travels across time, Kang had learned about the existence of Knull, and he knew what threat he represented to the entire universe. For that reason, he began to assemble a team of superheroes to stop Knull from ever plunging the cosmos into darkness. His first recruits were Rocket Raccoon and the Black Knight, and in the latest issue of the series, he also adds Monica Rambeau's Captain Marvel and Spider-Man.
When Spider-Man first finds himself face-to-face with Kang aboard his spaceship, he reacts as any superhero should. Kang is a dangerous Avengers-level villain, and Spider-Man recognizes him as such. The two briefly fight after the superhero attacks, but Kang stops the battle, insisting they are on the same side.
Peter Parker isn't all that ready to believe the villain however, so Kang has to explain himself. "I'm trying to save the universe!" the villain exclaims.
"And why would you be trying to save the universe?" Spider-Man asks.
"Because I live within it, you idiot!" Kang snaps back.
This reasoning is the same that Star-Lord exhibited in 2014's Guardians of the Galaxy. In the James Gunn-directed film, Peter Quill tries to convince his friends and fellow Guardians that it's up to them to stop Ronan and save the galaxy.
However, Rocket isn't all that convinced, which is why he asks him: "Why would you want to save the galaxy?"
"Cause I'm one of the idiots that lives in it!" Star-Lord tells him.
It appears that Kang is using the same logic as the MCU's Star-Lord -- he's even using the word "idiot," although he's directing it Spider-Man instead of himself. No matter where you fall on the superhero spectrum, whether you are one of the worst villains ever or an outlaw who hovers between good and bad, you can't keep what you're doing if there's no longer a galaxy -- or even a universe -- to operate in.
Thankfully, Kang has that realization, and he's now on the side of good...at least for the time being.