A decades-long project can extend Earth's expiration date, or snuff it out entirely. No pressure.
In a tumultuous world, you've learned to live in fear. Protect what little you have, because it can all be taken away. Everybody knows what happens when you fly too close to the sun.
Against your better judgement, you now have a house guest. Some would say you're harboring a fugitive. That's just a matter of perspective.
He's short on answers, and raises too many questions. He's brash, crude, and smarter than he looks. Is he flirting, or just using you?
Can this partnership survive on fleeting feelings of trust?
What isn't he telling you?
Can you discover his secrets without revealing your own lies?
Do whatever is necessary to survive. Hide your true feelings, misuse alien technology, explore each other's bodies, and betray your government like it's going out of style.
You're running out of resources, running out of time. You can't hide forever. You'll have to come out and face apocalypse, whether you like it or not.
Rise and shine cupcake, the future is now.