Pure speculation, but I wonder if David was initially intended to be a secondary villain in Life and Rory was meant to be the hero of the story but David was rewritten to be the hero when Ryan Reynolds had to drop out of the project?
⚠️ Speculations with spoilers under the cut. ⚠️
David is deeply traumatized from seeing the horrors of war in a Syrian warzone, he expresses his contempt for humanity on multiple occasions, he doesn't seem particularly close to anyone, it sounds like he might be estranged from his family, he's often off alone smiling to himself in a kind of unhinged way, and he describes Calvin as "beautiful."
Uncharitably he could still be read that way.
It's always David shutting the door on his crewmates--on Rory and on Sho. He and Miranda left Hugh's body for Calvin to feed on. Literally feeding his crewmates to Calvin. And while he was apparently very desperate to help Kat back in the airlock... it could have been a front and he was actually desperate to let Calvin back in--you can't enact your revenge against the human race if he suffocates outside.
Also during the doomed final plan of luring Calvin to the escape pod (the escape pod that is pre-programmed to automatically return to earth if anything happens to the pilot) he pointedly asks Miranda: "Do you trust me?"
For some reason that line stuck out like a sore thumb because at this point after all you've been through together why would that be in doubt? Have you given her a reason to believe you untrustworthy? Or are you planning or thinking something untrustworthy? Something along the lines of "I don't care if Calvin eats me so long as I can avenge this world?"
I don't think this is canon as he's written in the movie that exists though perhaps unconsciously he was hoping Calvin would destroy the human race...
