I love rare pairs so feel free to surprise me with a combo of Beholderites or someone from my 'regular' character list below. Have fun mixing it up in some new, exciting way (e.g. Trelawney/Moody, Xeno/Andromeda, Tonks/Stan, Dudley/Lavender, Molly/Arthur/Kingsley)
These characters make me happy: Tonks, Bill, Charlie, Luna, Ron, Neville, Ginny, Fred & George, Sirius Black, Kingsley, Pansy, Lavender, so inclusion of one (or more) would be grand.
I also love: assertive female characters, threesomes (if m/m/f please make sure to give equal attention to all the characters involved), bisexuality, angst, humour, banter, a/u, UST, sexual exploration, happy endings, EWE, true love, light bondage/discipline, spanking/strapping/flogging, Consensual BDSM, seduction, romance, kissing, shower/bath!sex, frottage, voyeurism, plotty stories vs. PWP, exploration of the Wizarding world or the use of magic in a sexual setting, first times or courtship – I love to know how and why a relationship ticks vs. a schmoopy established relationship with no explanation.
Molly/Arthur or Andromeda/Ted: if you use them, please don't split them up or have either cheating once they're married. If you feel the need to explore one or both with another character, then consensual polyamoury or a threesome would be just fine.
However, Andromeda/someone else post-war in an canon-ish setting as long as Ted doesn't die in the fic itself. Please keep Ted's memory alive and their previous relationship as something positive. Also feel free to keep Ted and/or Nymphadora alive if you want.
I really dislike: Alpha/Beta/Omega/Whatever It is universe. Non magical or Voldemort Wins a/u -- please stick to the magical Potterverse as we know it. Cross-dressing men(I honestly will be unable to read it/look at it). Character death (see caveat). Cross-gen relationships/major age disparity (see caveat). Unrepentant Infidelity/adultery. Next Gen characters or completely canon compliant stories. Female character bashing so if you can't write someone nicely, then please don't include them. If you need to break up a relationship, have it not work out vs. painful, horrible death or deceit, or just ignore them completely. I also dislike stories with name only characters (like Morag MacDougal or Stephen Cornfoot). Also please avoid the following tropes: "my male partner is secretly gay and that's why he doesn't love me, so I'm free to go with you", "poor scarred, damaged Lavender needs [Person X] to make her feel loved again".
Bestiality (including Animagi forms and humanoids – centaurs, merpeople etc.), Death Eaters, vampires, werewolves (esp. Werewolf!Bill or Lavender), cutsey non-canon nicknames, obsession with Muggle pop culture by Wizards (i.e. listening to current bands, reading American comic books or manga, watching 'Star Wars' etc.), Americanisms, piercings, anachronisms, gender fuck, body/gender swapping and Tonks-with-a-dick are all turn offs too. So are fanon cliches like angsty Lavender-with-scars or Tonks-changing-her-hair/eye colour-uncontrollably. Please stick to canon descriptions of canon characters wherever possible (e.g. Charlie is short and stocky, Millicent is a large woman, Andromeda is the middle Black sister, Tonks' eyes are dark, Viktor is not a male model.)
Caveats:
Character death: basically, I don't want anyone to die or have any reference to it in the story. If it's a canon character who dies in the books (e.g. Moody or Ted), then please don't kill him/her within the story or make it some kind of memorial flashback. That said, if you want to explore Andromeda making a new life for herself after Ted's murder, or Xeno coping as a single dad after his wife's death, then that's fine. I just really love happy endings and positive fics, not doom and gloom, or reminders that person X will be dead by the time the story is over. (I hope that makes sense!) Making it a/u and keeping them alive? Even better.
Cross-gen: I actually have no problem with the concept of adult characters being involved with an older partner as long as there's not a HUGE age disparity (let's say a span of about 10 years or so), particularly with anyone in Harry's age range. The only exception would be Tonks/Moody.