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Not sure about the first.
Second: depends on what the author knew when writing. If the author just didn't know (or forgot) the purpose of trophies in Predator society, then it's a Series Continuity Error. If the author did know, and was consciously writing this Predator breaking the rules, then it's Stealing the Credit for the xenomorph kill.
Third: I'd call Culture Clash or maybe Innocently Insensitive.
Awesome, thank you!
More from Aliens vs. Predators: Ultimate Prey, the story "Abuse, Interrupted."
First: the action enters the main character's perspective when an injured female Predator busts into the cabin, the Xenomorph she was hunting close behind. The Xenomorph is rather quickly dealt with, leaving the main character's abusive boyfriend as the last hurdle, and he's no match for even an injured Predator. Which tropes, if any, would be best? Disc-One Final Boss (for the Alien), Hero of Another Story or Offscreen Moment of Awesome (for the Predator, since the battle has clearly been going awhile before Jazz, our POV character, gets into it?)
Second: Jazz kills the Alien with a shotgun. The Predator takes its head as a trophy. Normally this is only done for the very best kills, the prey that proved most challenging to hunt. Jazz killed for her, but the Predator takes the trophy anyway. Is there a trope for that?
Third: after dealing with Jazz's abusive boyfriend, Jazz shooting him with the shotgun, the Predator takes his skull and spinal columns, and offers them to Jazz. Jazz, not understanding what these trophies mean in Predator society (to say nothing of the complications of carrying her dead abusive boyfriend's severed head around) declines. Is there a trope for that?