This is TEAL DEER like woah, apologies, but I am pretty easy to please, anything that doesn't hit my squicks and has a happy/not-actively-sad ending will be amazeballs, and I'd much rather read something you've enjoyed writing than you trying to fit into my likes (Holy run-on sentence, Batman!). But I've got down some broad 'these things are my catnip' and some broad ideas per pairing for what I like. So! Lets kick off.
Generals: Epistolary fic! Give me feelings over email, text, post-it note left of computer screens. Love it.
I love pining, and domesticity. I also love found family stuff, so throw in some bffs if that's your thing too.
Science! Its no co-incidence there are some science dorks on this list. I adore geniuses being genius at their thing, and I have a competency kink a mile wide, so give me Cisco, Barry, and Hank being A++ scientists, give me Charles cooking up something amazing in two seconds, give me Jake and Ray solving a crime together, give me Malcolm being excited over tactics and strategy.
I love fics about falling in love, and not necessarily ones with lots of UST or silly people being silly puppies/obliviousness. Curtain!fic, and fic about earning to live with each other, is pretty wonderful. My two favourite films are Before Sunrise and Before Sunset, quiet films about falling in love and connecting. There's a quote from Before Sunrise, that sticks with me: If there's any kind of magic in this world it must be in the attempt of understanding someone sharing something. I know, it's almost impossible to succeed but who cares really? The answer must be in the attempt.
Kinks: I am happy with any rating of fic, but if you do want to throw in some sex, I'm pretty open, people being into it is the dealbreaker. I want enthusiastic sex, and loving sex, and kinky sex and awkward sex (where both people find it funny, rather than embarrassing). If you want specifics: [Spoiler (click to open)]Rimming/felching, blowjobs (I have an oral fixation, ok?), first times, fingerfucking
Squicks: Non/dub-con, humiliation, and Mpreg are my biggest squicks. No major character death either outside of canon deaths, please. Oh, no character bashing.
The Flash: Barry/Cisco
Sciencebros in love! Cisco helping Barry find the limits of his power. If you want to give me Vibe!Cisco finding out the limits of his powers I will love you eternally (Cisco getting trained in hand to hand contact? Cisco realising he's now super agile? Can Cisco use his vibe powers to sense where Barry is in the city?).
Enterprise: Jonathan/Malcolm
Falling in love despite themselves? Bonding over Eagle Scout badges? Pining because of duty and having a not!relationship instead?
X-Men: Hank/Alex
Post-beast/1st Class pining? This I feel is a another pairing where 'For Science!' could be a reason for Hank getting Alex to do things to figure out powers and control and limits.
B99: Charles/Jake Undercover dorks in love? Jake trying to get Charles food good enough for him and failing miserably but Charles being overjoyed that Jake tried?
Kevin Cozner/Ray Holt Tell me get togethers! Tell me about young!Holt on the street, running into young!Kevin whilst fighting crime.
Ray Holt/Jake Peralta Do I need to talk about mentor/mentee relationships here?