Venom: What Does The Ending Really Mean?
2. Eddie And Venom Have Agreed To Co-Exist As A Lethal Protector
When Venom and Eddie first bond it's a pretty one-sided relationship. Sure, the symbiote is keeping his host alive when he's being chased by goons, but it's made clear that the alien is in the driver's seat, free to bite off heads and push forward with his race's grander aim of invading Earth.
Somewhere along the line though he and Eddie discover a connection deeper than simply stopping each other from dying, and Venom decides to screw Riot and the rest of his people and co-exist with his new friend on Earth. The main reasons he gives for this change of heart is that he, like Eddie, is also looked upon as kind of a loser, and he also seemingly falls in love with Michelle Williams. Both very valid reasons for turning to the light side.
The final scene shows that they've come to an agreement: Venom will only eat the brains of bad guys, and Brock can use his newfound power to once again help people like he did when he was a reporter. He's turned down being reappointed at his old job, and focusing, as he says, "on the written word", most likely while being a lethal protector at the same time.