I think it's a fundamentally bad idea to write fic for a blank exchange signup in a Yuletide-sized fandom based on the sourceless assumption that they are contact with any existing fandom, aware of and agree with prevailing opinion about what they should dislike about the canon, and that following the consensus fanon held by a bunch of other people would be a better gift for them than something that's actually similar to canon. Absent other cues, the canon is your prompt.