Certain words and phrases aggravate me to no end when I see them in a sex scene. The entire rest of the fic can be well-written and even the rest of that scene and I see a woman's lady bits referred to as 'her sex' and I'm rolling my eyes and leaving the fic. Most of the cheap romance novel style alternative names for a penis have the same effect. Also, porno style dialogue during sex. Usually it's eye-rollingly bad, or seriously too articulate for the point they are at in the encounter. Maybe if it is the kink of one of the characters to listen to dirty talk during, well realistically, probably mostly during the foreplay, but if it's their first time, they shouldn't know that. A lot of people would be rather upset by hearing dirty talk, especially the kind that involves certain words, so characters who don't know each other very well, and certainly haven't had extensive discussions concerning each other's kinks probably aren't going to bring it up the first time.

Although that could make for a good scene. Two characters get to the bedroom. They've gotten naked, and one of them starts in on the porno quality dialogue, and the other one just looks at them and laughs. I'd like to see that sometime, but then I read shipfics for the relationship more than the porn. (There is always PWP if you are just looking for porn)

Another one that I see over and over and over is the whole 'kiss swollen lips' thing. Seriously. If your lips are noticeably swelling after kissing--you're probably doing something wrong. Apparently there is some biological basis for this, that can be measured in I don't know, maybe micrometers? I'd be more likely to believe that they end up with chapped lips the next day from the saliva. Maybe it is reasonable to say that their entire face was flushed, and therefore their lips are redder than usual, (but I think only a very pale Caucasian character would even have that effect. I am extremely, eye-blindingly, is that a snowman?, pale and I've looked in the mirror and...nothing. I've asked a friend who has a much broader than average level of experience--she's never seen anyone's lips swell and turn red after kissing or any other activity.) I see this in a fic and I automatically think, "This is an extremely real life inexperienced author who is simply repeating the acts they've read in other fics with no real reference." I read one fic that had a character portrayed as asexual and the character thinks about this trope and it's just kind of a weird thought to him. I'm not asexual, but I feel the same way about this particular trope.

Another thing is characters that have been working in hot, sweaty conditions all day, then they strip and get to sexy times (including oral sex) with no shower and no mention whatever of the natural consequences of being hot and sweaty and 24 hours or more since their last shower. (And I'm reading it thinking, ewwww)

On the first time being perfect, even characters who are experienced, if it's their first time together, it shouldn't be perfect. I read one the other day that was a great fic. The characters fell over, got tangled up in their clothing, ended up laughing over each other's clumsiness, and there was other general fumbling. It was all very real. A nice change of pace on all those where everything is porno perfect.

Actually, sex between average characters should probably never be porno perfect. If the fic is supposed to be about characters older than 30-35 (and the characters on a lot of live action TV shows and movies are), especially if they have been together for a few years...they are over the initial rush of each other and past the extreme hormones of youth. There should be shorthand where they know the other is actually too tired, but hey it's sex, so they'll give it a try (and if they do go ahead with it, it's really more 'meh' than anything). Where they don't do it every night, and they are too old to do it multiple times in one night. It doesn't last all night (and if they are really being honest with each other, there was probably only that one time where they even did the whole 'sex all night, and 8 orgasms' thing as 20 year old kids). They probably have a whole repertoire of things they do that aren't vaginal/anal intercourse (when they're tired, when they aren't really in the mood, when they want to get off, but don't want to put in all the effort). Really, everyone wants to believe that all sex they have will be mind-blowing, but it'd be nice to see fics with established couples admit that it isn't. And especially with slash, it would be nice to see new couples that don't go directly to anal. I'm sure some couples do that, but there is a lot of range that could (and probably should) realistically be in there first.

My general motto is to ship the teenagers with other teenagers, and ship the adults with actual adults. Especially if your thing is set after canon: if it's after canon, you can set it five years after canon so that characters can pass their age of majority and gain some badly needed life experience on the way. Maybe then if you can write well I'll believe that they could make a relationship with a somewhat older character will work.

... This is also one of the tropes that makes me really wary of fics that are high school AU's, especially when an attractive character is made the teacher.

Always in Repair a Final Fantasy XIII goodfic that I've read not too long ago. Written before XIII-2 came out, it ships Hope and Lightning in a plausible way. Even though their ages are seven years apart in canon and Hope is underage (14, as opposed to Lightning's 21), the author manages to fix the issue plausibly (in-fic, Lightning emerges from crystal stasis when Hope is 19) and develops the relationship very realistically. If you are at all interested in FFXII fic, I'd highly suggest this one.

... I'm aromantic. So while I agree that a lot of people (the vast majority of people, probably) are going to identify with romance in the story, I wouldn't call it "integral" to humanity - at least, not to all of the humans.

/ personal nitpick.

The OTP enforces a sort of hierarchy of shipping in someone's mind, and perpetuates ship wars when different hierarchies of ships clash with one another.

You could have one ship that you write more or read more fic about (Spirk, for me), but that doesn't necessarily mean it's the Ship To End All Ships because there'll always be someone who thinks you're wrong. I may like Spirk, but that doesn't mean I can't appreciate Spuhura, or McKirk, or Spones, etc.

(I just like pairing Spock with people. Poor baby is all alone out there being a hybrid.)

Incest is pretty creepy. And extremely out of character for most sibling pairs.

But there are some exceptions. Luke/Leia? Could work. They grew up apart. Their immediate disgust on learning about their blood relationship told us they weren't going to try it, but an AU where they got farther than a kiss before they learned about it? Plausible. Vaguely disturbing, but plausible.

Then there are stepsiblings whose families combined after they were at least pre-teens--too old to think, "Ew, that's my brother/sister!" On a darker note, some characters have simply had a messy enough background that incest makes sense (and besides, they've experienced or done much worse). Not that this would be a romantic story... more like desperate and a bit offputting. But it can and does happen. Without a power difference between the siblings (physically or psychologically), it may not even be abusive.

Some historical families didn't have quite so strong an incest taboo, though they did have to work around the "ew, that's my sibling" reaction, usually because siblings grew up apart (royalty, anyone?). Once you get to first cousins, it's pretty much a toss-up over whether a romance is possible, and in some cultures is even recommended.

And once you get to sci-fi aliens, fantasy races, robots, intelligent shades of blue... well! "Incest" may lose its meaning for someone who is built not born, or who has sixteen thousand siblings, or who reproduces by growing babies in the gigantic seed pods of a specially engineered plant.

For most characters, incest is out of character and highly improbable. But there are exceptions.

A couple of personal pet peeves of mine are making ACD Sherlock Holmes a passionate, love struck, sex-crazed mockery of himself, and making a Stargate Atlantis Wraith want to have sex with humans. Firstly, they are hive creatures descended from insects with only a few queens, so the odds of them ever getting to mate are slim and following the insect model probably requires some kind of pheromones from the queen to trigger the desire to mate. And secondly having sex with humans is equal to bestiality. Humans are their food. The only Wraith who it might be realistic to say thought that way was Michael and he had been turned human at least once and ended up being a kind of hybrid between humans and Wraith (and the other Wraith kicked him out for being contaminated). A full Wraith has no business thinking that way.

A. I have to disagree a little with point 1. Just because someone grew up in the 1930's does not mean they never encountered homosexuality. If they encountered it, they might have thought about it. (They might have gone with the ingrained homophobia of the times and been repulsed by it automatically, but they might not have.) Saying that Steve would never have thought about it or encountered it before is putting too much innocence on him.

My point is based on hearsay, my grandpa was in the Navy in the early 50's. There were apparently a lot of...encounters going on in the bathrooms in certain ports, and his opinion was that if they left him alone, he was going to leave them alone. He wasn't much younger than Steve Rogers, and was from a rural and more strictly religious region than New York City. If he could have that kind of opinion, why would Steve (and every other man from the era) automatically have to have a bad opinion of it?

I do agree that there should be an exploration of that in a good 'getting together' type fic. Shippers need to think about the orientation of the characters, and where they came from. It needs to be addressed, but I don't think in Steve's case he'd have to start out hostile to the idea. Maybe more likely to be hostile to the concept that it isn't a social taboo anymore.

B.Not all fics have to be 'getting together' fics. Some fics are just porn (and sometimes that's okay). Some fics are about an established relationship. Sometimes they are just short fluff fics about having breakfast in bed, or watching a movie, or washing the dishes together. They aren't life-shatteringly important, no, but sometimes it's just nice to see a couple get to have a day off, and bringing in exactly how they ended up together would mess that up.

Example: I am reading a series of fics about Phil Coulson and Clint Barton as retired old men--I don't need to know about the difficulties they faced overcoming homophobia as young men. The series is not about sex. It's about loving someone that has wrecked their body (if he survives to 65, is there any other outcome for Clint the way he lives?). It is a heart wrenchingly good series. Trying to shoehorn in an exploration of how they got together or why they are both gay in this story would take away from the story.

C. Sexually active people do think about sex quite a lot. If a character is not in a situation that would make them be not interested (they're hurt, sick, hungry, in a life or death situation, but even in cases like this, even when they aren't physically up to sex, it doesn't mean they aren't wishing they were), then it probably should cross their mind. Especially if they are seeing or thinking about someone that looks like a good potential mate. Even if they are married or in a committed relationship, sex tends to run through people's minds (obviously not through an asexual character's mind, or maybe not someone with a very low sex drive, but someone like, say Tony Stark, since he's already been brought up. Until the PTSD gets bad, he should be thinking about sex frequently).

Obviously, they shouldn't be acting on every passing thought. I think badfic tends to think that a character can't appreciate the view without wanting to get naked. Badfic also tends to ignore social taboos that a person would normally operate under. Whatever a person might fantasize about, they aren't likely to strip and start having public sex or to jump into bed with handful of near strangers, or even if they did have an orgy with friends, sex changes things between people. It's rarely ever 'just sex' in the real world. Emotions get involved. Things change between people when the emotions get involved, and true multiple pairing relationships aren't that common in the real world because of that. That has to come up in the shipfic, too.

D. I'll be in the minority on this thread and admit that I do like reading shipfics. I have to say that I didn't always like them, though. When I was reading/watching primarily canons that weren't rife with UST, where the characters actively hated each other, actively were involved with other people or had reasons they were't involved with anyone--I didn't like shipfics. I thought I just didn't like them period. Now I am in a couple of fandoms that have either a firmly established fanon ship (Phil Coulson/Clint Barton), or there is just a ton of UST in the canon (Haven between Audrey/Duke/Nathan). I have come to really enjoy shipfics in those canons, and it has kind of spread from those relationships to others.

I still have fandoms where I am just not very accepting. I'll never accept incest fics. Supernatural fans frankly tick me off with their obsession with having brothers have sex. I don't read shipfics in LotR pretty much at all--especially with elves. Their author stated it is biologically impossible for them, so word of god is that shipfics shouldn't exist for them. There are others. Some, I can be convinced, but it isn't automatic. The first slash I ever liked was in NCIS. It took 35,000 words to get to the point where it made sense for there to be a kiss.

When I first joined the PPC I thought there was no such thing as good slash, because all I had ever seen was Bad Slash--bad for a lot of the reasons you mentioned. I wouldn't even look at a fic that had a ship that wasn't present explicitly in canon, and I never considered that a character might be something other than straight in a case where it isn't specifically mentioned in canon. I've expanded my thinking since then.

E. Pulling characters toward stereotypes to facilitate the ship. This has been touched on in other posts, but I just wanted to put it out there explicitly. If you are dealing with two hyper masculine men who canonically are seen appreciating women, but canon has nothing to say about their appreciation or lack thereof of the same sex, then making one or both conform to the worst stereotypes about gay men being feminine, whiny, flamboyant, etc. is so far out of character as to break canon. I will read slash about those men, but the author has to convince me that these are the same men I see in canon. They have to come together believably as two very masculine, alpha males. It is entirely possible to write this and do a good job with it. It is more likely to be done badly, though.

Everything you said, and more

6. Bashing characters in order to make a ship "work."
Maybe the pairing remains within an arm's reach of their normal characterization, but a canonical love interest gets bent out of canon in order to make room for the ship. (This happens in a lot of Spirk AOS fics: Uhura is either written out, as in most AU's, turns into a complete bitch, or is somehow quickly removed from the equation, usually by shipping her with someone else, in order to get Kirk and Spock together.)

7. Not understanding that not every close relationship is sexual.
I think this goes with out saying, but lots of ficthors forget that most human beings are capable of having friendships where they have no sexual feelings for the friend, and there's plenty of psychological failsafes in place in the human mind to keep incest down, such as the Westermarck effect. This lack of understanding is, I think, the root of a lot of incest fics. For example, I do not care that Thor and Loki are not biologically related, they were raised together from infancy, it's still a no.

8. Power differentials that would make normal people run for the hills.
Authors of fanfiction often forget to add characterization that would reassure me that one member of their pairing, usually the one with more power or experience, isn't just horribly using the other. Sometimes, I think this also comes from point 7: people who decide to make a mentor & student relationship a sexual one in their fanfic, for example, are unlikely to do anything to reassure me that the student, even if of age and capable of giving informed consent, is not being somehow manipulated into the relationship, either overtly or because they think they should do it to please their mentor.

9. Lack of representation. This nitpick ties into 1, 7, 8, and 9. Most fanfic authors assume that all romantic relationships or primary partnerships are sexual, and they often try to overwrite actual character dynamics in order to achieve that. But in general, fanfic ignores friendships and relationships that are purely romantic, and treats them as a mere stepping stone to a sexual relationship, even with asexual characters. They also tend to state things like "no, Tony Stark is pansexual, he'd totally sleep with Steve or Clint" and then, once they've shoved him into the pairing, never give a thought to it... rather like writers who seem to forget that characters can be bi or pan and only concentrate on their current relationship, but you'd think that fanfic authors, many of whom have at least some education on the matter, would be a little better at it. (Some of them are.) Another thing that fanfic authors don't often think about is whether or not the sex drives they've written for the characters are reasonable. Going back to Marvelverse, it's pretty well established that Tony Stark's libido before he became iron man was pretty high, so it could still be pretty high despite clear signs of building PTSD and the arc reactor in his chest. Maybe even high enough to mostly justify the amount of sex they're writing into the fic: but like real humans, other characters will have varying libidos, and writing every single pairing having sex at the drop of a hat is pretty ridiculous.