Here's another one, which I posted on my personal Facebook as well:
This time, I was a trained alien assassin who could take down just about anything thrown at me. The Earth had been invaded by huge aliens, and the remaining humans were in an enclave trying to survive the onslaught. I and the other alien killers were able to hold the line for a while... but eventually they sent in big enough creatures that we knew our time was limited.
So, in a desperate bid for survival, the government started a program to try and combine the two races - and they basically handed me a tiny alien kid to raise and study, with the knowledge that if he turned evil, I'd have the know-how to stop him.
Only... I got attached, and when the time came to send him out as essentially an agent of chaos to take down the aliens from the inside... I didn't want to send him. Which is how I found myself instead being smuggled by the boy into alien society. By this time, I was old and gray, but some of the aliens remembered me, and the integration was rocky. But, y'know, he tried. And we sort of accidentally ended up turning ME into the agent for change and peace.
Eventually, we came to an agreement, with the aliens agreeing to give humanity time to evacuate Earth with what little population we had left... but I ended up staying with my adopted alien son and being buried there.
I mean on the one hand, it's an epic action movie dream. On the other, I may have had adoption on my mind now that our home study paperwork has been sent in for review...