i love: hidden motivations and extended sexual tension; first-time sex; unreliable narrators; characters who seem like they should be opposed but working together (ETCETERA!); wartime and post-war stories of shared experiences and coming to terms; inventive magic, magical theory or wizarding logistics, in as much as they serve character or plot; slytherins!; muggles!
as for non-beholder characters, i would be delighted to write/receive snape, malfoy (d), potter (h), weasley (r), or lupin as part of a pairing.
i don’t get much out of: fuzzy established relationships; relationships that make no sense in terms of the canon (i.e. they never met or had cause to meet); characters i just don’t know at all from the books – effectively ocs. on the other hand, i like a well-written oc sometimes (especially muggles!) – no need to give them a canon name.
i am very triggered by serious illness – and death as a result of illness (as above) – so please no mention of this at all.
beholder-y preferences: formal intellectualism for its own sake doesn’t do it for me, so i’m less interested in characters that canon or fanon considers ugly coming off as stupendously bright than i am in seeing (or writing) characters whom canon or fanon considers stupid showing humane intelligence, or unexpected pragmatism, and achieving (sexual) success or value of whatever kind because of that.