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things like endometriosis can develop in an estrogen-dominated system, because its the hormones that cause the growth of endometrial lesions, not the “parts” themselves. If you’re experiencing unusually painful symptoms* then you have a right to find a doctor who will take you seriously and not try to gaslight you into thinking that the pain is “normal”.

TW for medical descriptions of anatomy and referral to the anatomy as "male". Emphasis is mine.

Since Oliker and Harris published “Endometriosis of the bladder in a male patient” in the Journal of Urology in 1971, there are about 20 case studies in the scientific community. The majority of these cases have two things in common:

1. The endometriosis lesion occur along the path of cells laid down during early embryo and fetus development. The majority of these cells normally ‘regress’ (disappear) before being born. However, it’s normal for a small portion of cells to remain after birth. These cells are inactive, dormant. They are referred to as embryonic cell rests. In development of endometriosis lesions among males, it’s suggested these cells are stimulated and continue to differentiate. Lesions that develop into ‘endometriosis’ present with specific characteristics to include glands, stroma and hormone receptivity to estrogen and progesterone.

2. Elevated circulating estrogen is suggested as a stimulating factor in most cases.

What I mean by that is that, while you can see how many fics are tagged in each category (M/M, F/M, F/F, Gen, etc.), for example, you can't easily capture how popular fics in each category are relative to each other.

NCIS shows a clear example of this problem and how it complicates determining what is "popular" in fandom: as of June 10, 2026, there are 8424 Gen fics, 8093 F/M fics, 7483 M/M fics, 1029 F/F fics, 685 fics, and 246 Other fics tagged to NCIS on AO3. From those numbers, you would think that Gen and F/M fics are more popular than M/M fics, because more people are writing them.

However, the most popular fics are virtually all M/M fics. 18 of the top 20 most kudosed fics are M/M, while only 4 of the top 20 are F/M (fics can be multiple categories, and 3/4 top F/M fics are also M/M fics), and 1 of the top 20 is Gen. This holds fairly consistent for at least the top 100 most kudosed fics in the fandom. So based on what fics are popular, M/M is by far more popular than the other categories in the fandom. People respond more positively to them; they do better in the fandom.

Unfortunately, kudos distribution is basically impossible to collect at scale. Unlike category, which is collated by AO3, kudos data has to be gathered entirely manually, which means looking at literally every page. And for fics with multiple categories, that means opening each fic to see what categories it is tagged to. There's just no practical way to collect that data on a large scale.

(Yes, you can write a script to collect it for you. Yes, AO3 will rate-limit you fairly quickly. AO3 rate-limits me regularly doing regular manual data collection.)

We run into a similar problem when it comes to looking at character popularity. We can see how many fics a character is tagged in, but not only do we have the same kudos popularity issue, but there's also basically no way to tell whether characters are being tagged as a primary vs secondary character purely from the numbers.

Natasha Romanov is the fourth-most tagged Marvel character on AO3, but she is rarely the main character of fics she is tagged in, and those fics where she is the main character tend to be less popular (fewer kudos) than fics where other (male) characters are the main character. So the data we can easily collect say that she is one of the most popular characters in the Marvel fandom, but looking at both kudos numbers and the fics that she is tagged in tell us that that's not really accurate.

I'm guilty of that too. It's what's easiest to talk about.

But you lose a lot of what really drives representation disparities in fandom, which is not just that people tend to write more about certain types of characters in a literal number sense but that certain types of characters get more positive responses, get more engagement, are more likely to be the main character of fics they are written in.

It's not just "people write more about white male characters" but "white male characters are more likely to be the main characters of fics they are in, and fics about white male characters receive more positive responses in general, while fics about other characters receive fewer positive responses in general."

Without numbers behind all of this, it's harder to show intellectual honesty behind the conversation. You kind of have to take my word for it in a way that is less true when I have numbers to show you.

and he paused for a second and then said, “when you’ve been taught from a young age that crying is weak and you should train yourself never to cry for any reason, you assume that everyone else has trained themselves too, so anyone who cries has to be doing it on purpose. it took me a long time to realize that wasn’t true.”