I have a few:
- Chosen ones, fate, destiny, &c. When you get down to it, a story with these themes is one where a single person or handful of people is ontologically, cosmically better and more important than everyone else. It’s eerily similar to that right-wing meme about how “most people are just NPCs” (though I disliked the trope before that meme ever took off).
- Way too much importance being given to bloodlines by the narrative (note, this is different from them being given importance by characters or societies in the story).
- All of the good characters are handsome and beautiful, while all of the evil characters are ugly and disfigured (with the possible exception of a femme fatale or two).
- Races that are inherently, unchangeably evil down to the last individual regardless of upbringing, society, or material circumstances.
A More Civilized Age discussed this exact point recently; There’s a very valid reason for resistance fighters to not take prisoners. One, keeping prisoners requires resources you may not have. But more importantly, the goals of a resistance group and the goals of the occupier are not the same.
As a resistance group your goal is not total military victory and occupation, your goal is to make continuing the occupation as painful and expensive as possible, to convince the occupying force that continued occupation isn’t worth it. Taking prisoners directly goes against this goal, unless you plan on using those prisoners as some sort of bargaining chip. Especially in a sci-fi setting where wounds can be healed quite quickly and thoroughly and so the wounded can be back in action very quickly.
And YES! They would have done the same to you! Without hesitation! And they still might try if you don’t kill them!