What are the smuttiest ships?

This post is a reaction to standbyyourmantis’s post who raised a most interesting question: what is the smuttiest ship?

We used individual data on the fics published in 2015 on AO3 to answer (to have a manageable data set, we looked only at fics longer than 10000 words … but that is already 75000 fics!). We computed the stats on smut for the 100 most popular central ships (see there for the details), that is fics classified according to the first ship listed in the description.

Why is it important to classify stories by central ships ?
Some numerically important ships are mostly secondary: for example in Supernatural, Sam/Jessica is quite a popular ship in numbers. But it is almost never the central focus of a ship, but rather a background ship, popular because of the canon, in Destiel stories. By classifying according to the first ship listed we avoid:

  •  counting the same fics twice or more (e.g. the same fic as a Sam/Jessica and as a Dean/Castiel fic)
  • observing “irregularities” (e.g. tags for gay sex in tories labelled Ron/Hermione simply because most of these stories are actually about Harry/Draco)

1. Slash is smuttiest than het or femslash

Archive of Our Own is known for allowing all sorts of explicit material. The site uses the following rating system:

  • General Audiences
  • Teen And Up Audiences
  • Mature
  • Explicit: only suitable for adults

There is aslo the possibility of not rating.

The TOS FAQ states that the difference between the ratings “is left to the creator’s judgment. People disagree passionately about the nature and explicitness of content to which younger audiences should be exposed. The creator’s discretion to choose between “general” and “teen and up” or between “mature” and “explicit” is absolute: we will not mediate any disputes about those decisions. Instead, we encourage creators to consider community norms, whether fandom-specific or more general (such as how you’d expect a video game or movie with similar content to be rated), in selecting a rating.” (from https://archiveofourown.org/tos_faq on 28 June 2016)

If we concentrate on the rating Explicit, the 15 smuttiest ships are all slash :

Whereas most of the 15 ships with the less smut (less than 13% of fics rated Explicit) are either femslash or het.


So at the first glance, slash seems to be much smuttier than het or femslash!

Highest F/M pairing in terms of Explicit fics : Sandor Clegane/Sansa Stark (35% of fics rated E)
Highest F/F pairing in terms of Explicit fics: Root/Sameen Shax (24% of fics rated E)

Actually, het and femslash with smut tend to be rated Mature rather than Explicit. For example, the Delphine/Cosima pairing, or Clarke/Lexa have very few Explicit fics, but a lot of Mature fics.

The 15 ships with the highest percentage of mature fics:

This is the opposite for slash.

The 15 ships with the lowest percentage of mature fics:


Does slash tend to be more often rated E than het or femslash because it actually contains more explicit sex scenes? Or do community norms differ in considering what explicit sex is depending on whether the protagonists are male or female?  I tend to favor the second option but it would be really interesting to investigate.

Rather than making many tables, one can summarize the differencies and similarities between our 100 ships in terms of rating by maping them on a single figure.

Principal components analysis is a mathematical technique that allows such simplification of the data. For those who don’t know about principal components analysis: here is a rather accessible explanation, or “PCA explained to your grandmother“.

In broad lines: for each of our 100 ships, we have the percentage of fics classified General, Teen and Up, Mature or Explicit. First, PCA shows us which ships have similar repartition of fics rated according to these 4 criteria, and which ships have very different repartion.

Second, PCA summarizes these five criteria in two: the two axis on our graph.

What distinguishes most ships is whether they have a high proportion of smut (Explicit and/or Mature fics, to the left) or not (to the right).


PCA took into account only the proportion of fics for each ship rated G, T, M, or E, and not whether the ship was slash (M/M), het (F/M) or femslash (F/F). However, what appears on the graph is that slash, het and femslash ships are not located at the same place. Slash ships are mostly located on the lower half, whereas het and femslash ships are mostly located on the upper half. This means that knowing only what proportions of a fics for a ship are rater G, T, M, or E can allow to predict with relative accuracy whether this ship is slash, het or femslash.

The variable that is the most highly correlated with the vertical axis is the Mature rating. This means that this rating is disproportionately used to rate ships including female characters, that is het or femslash. Slash emcompasses relationships with the most diversity in types of fics: some are highly smut oriented (Dean Winchester/Sam Winchester, Loki/Thor …), others contain mostly gen stories (Nico di Angelo/Will Solace, Hinata Shouyou/Kageyama Tobio …). On the contrary, even when relatively smutty, femslash pairings give birth to stories with still a high proportion of T or G ratings. For example Delphine Cormier/Cosima Niehaus, the smuttiest femslash pairing, has 36% of fics rated T or lower, whereas for Dean Winchester/Sam Winchester, the smuttiest slash pairing, this proportion is only of 11%. Against, this can be because of an actual difference in content, as well as different traditions in rating slash and femslash smut, or differences of perception of what is sex between men vs. sex between women or between men and women.

2. Differences in warnings

Authors can chose to complement the rating with some warnings. Does their use also vary between slash, het and femslash ships?

There are four possible warnings to chose from: Underage, Rape/Non-Con, Graphic Depiction of Violence, or Major Character Death.

PCA reveals that the main opposition is between ships where a relatively high proportion of fics use those warnings, and ship where almost no use is made of those warnings.


Most of the ships, and F/F ships particularly, have a high proportion of fics with no warnings (to the left). Only slash ships and a few selection a het ships dinstinguish themselves by having a high proportion of fics with warnings. Non-con and underage warnings are almost always applied for slash.

The most violent ship is, not surprisingly, by far Will Graham/Hannibal Lecter, with 42% of fics with a warning for Graphic Depiction of Violence (against 29% for the second most violent ship, Female Shepard/Garrus Vakarian). The ships with the most fics rated Underage are Peter Hale/Stiles Stilinski (16%), Sebastian Michaelis/Ciel Phantomhive (14%) and Dean Winchester/Sam Winchester (12%). The ships with the more Rape warnings are Aaron Hotchner/Spencer Reid (9%) and Harry Potter/Severus Snape (7%). The ships with the most Character Death warnings are first: Spike/Buffy Summers (16%), then Gavin Free/Michael Jones (14%), and Bill Cipher/Dipper Pines (13%).

3. Differences in tags

Additionally to rating and warnings, authors label their fics with tags or freeforms, to help readers find what they want or do not want to read. Agains, the use of these tags varies extensively depending if the fics are centered around M/M, F/M or F/F pairings.

There is an infinity of tags that can be applied to a fic. Authors can invent their own tags, so we limited ourselves to the 50 most important tags for M/M, F/M and F/F respectively, for our fics (that is the fics pertaining to the 100 most popular central ships). Since many tags are employed in M/M as well as in F/M or F/F, this gives a total of 83 different tags.

Here are the 15 most employed tags for slash, het and femslash:


Again, PCA reveals that the use of tags is different between slash, het and femslash. On the following graphic, only the 30 most explicative tags (over 83) are represented (with dark red arrows) to keep the result readable.


On this graph, the distinction is pretty clear between slash (to the right) and het and femslash (to the left). Most of the tags that are strongly correlated with this horizontal dimension are specific to sex: blow jobs and hand jobs, rimming, anal sex, dirty talk, first time. In theory, those terms could be employed to describe sexual relationships between any gender, or, in the case of the first two terms, at least for heterosexual relationships. But what the graph shows is that are employed almost only in slash writing. By reading any of those tags, you can predict rather certainly that you are going to read slash fiction.

The issue of homophobia appear to be only tackled by slash fiction, and relatively absent from F/F fics (it is nonetheless possible that it is present in F/F fics, but not tagged accordingly). “First time” seems also a tag disproportionately present in slash. This does not appear on the graph but this is because authors of F/M fics tend to favor the tag “loss of virginity” in many cases.

There is also genre differenciation. All four are popular genres accross all ships, but Romance and Drama are more used in F/M whereas Angst and Hurt/Comfort are more used in slash. A/B/O is also mostly a slash genre.

Again, femslash stories appear specific. They are less tagged than other fics, and rank lower on the vertical dimension, which is linked to sexual content (Sexual Tension, Explicit Sexual Content).

Finally, some ships are highly atypically tagged. For example, Jack Harkness/Ianto Jones, Brian Kinney/Justin Taylor or Nico di Angelo/Will Solace stories are closer to the average femslash stories (the big red dot) than to the average slash story (the big blue square). Inside a same fandom, different ships can lead to different genres. For exemple, for The Hobbit, Fili/Kili (north-west quarter -rather typical slash, relatively close to the big blue square that is the average slash ship)  is quite far from Bard of Laketown/Thranduil (middle left – nearly unplotabble but just a little bit higher than Leo Fitz/Jemma Simmons), the latter being closest to the average het ship (the big green triangle).

What have we learned?

  • The smuttiest pairings are slash pairings. Among them, Supernatural fans are those who write the greatest proportion of slash stories, when they are interested in Dean/Sam, or Jensen/Jared for the RPF
  • Fics focused on sex with female characters, whether het of femslash, are much more likely to be rated Mature than Explicit
  • Slash, Het and Femslash are actually literary genres. They do not tackle the same issues and may have different policies regarding tagging, warnings and rating
  • Slash is the more diverse of these genres. Some very popular slash pairings give birth to fics with a high proportion of sexual content, violence and potentially disturbing content (Dean Winchester/Sam Winchester, Harry Potter/Severus Snape, Loki/Thor, Will Graham/Hannibal Lecter …). This type of content is quite specific to slash and seldom present in F/M or F/F stories.
  • Despite this fact, there are also a great number of slash pairings that are milder, with fewer sexual content and less violence (Nico di Angelo/Will Solace, Matt Murdock/Foggy, Sirius Black/Remus Lupin or Hinata Shouyou/Kageyama Tobio and Iwaizumi Hajime/Oikawa Tooru from Haikyuu!! for example).


Edit : following a question asked by extra-penguin on tumblr

extra-penguin noted that as shorter fics tend to be more G/T rated, there is a bias with looking only at longer fics. This is obviously true: fics longer than 10K words are not representative of all the fics posted on AO3. However, our general picture could still give an idea of what happens for all fics if the relative position of each ship does not differ when we look at fics longer than 10K words and when we look at fics shorter than 10K words. In order to have an inkling of the likeliness of this statement, we looked at the proportion of fics rated explicit for the 20 most important ships as given by the AO3 search engine.

In the following table are depicted the total number of fics and the number of explicit fics with more than 10K words (columns 3 & 4), the total number of fics and the number of explicit fics with less than 10K words (columns 5 & 6), and the proportion of explicit rated works for fics with more and less than 10K words (columns 7 & 8). The proportions as well as their correspondent rank are highlighted in green in ascending order to facilitate the reading.


Please note that the number of fics longer than 10K differs from the previous tables since the search engine gives all fics staring the corresponding ship and not the fics having the ship in first position as we did in our analysis.

For those 20 ships, the overall picture does not differ strongly for fics under and over 10K. The smuttiest ships for long stories are also the smuttiest for short stories. In  particular, the top 5 stays the same. The PCA results for ratings could thus be similar for shorter and longer fics. However, the bias of having selected only long fics may possibly stronger for warnings and tags.

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