Your earlier, cursory web search when you first arrived in this reality had already told you that general body type was not associated with genitalia in the same way you were used to: both men and women could have a penis, a vagina, both, or neither; so this world had eight genders. But being now one of those vagina-men, it was apparent to you that thinking of your self just as a man with a cunt instead of a dick was an oversimplification: there were…other changes, and a more in-depth reading of this world’s anatomy was called for. Your studied revealed that in this world, humans had two sets of sex chromosomes: one governed general body type and one determined your genitalia.
Men and women here were roughly analogous to men and women back home, but the double male and double female chromosomal arrangement amplified some characteristics. This world’s men and women would not look at all out of place in our world, but their average characteristics skewed higher than our average. The average male height here was 1.9m compared to 1.7m back home and men are generally more muscular—the eye-popping, sexy-but-not-over-the-top physique your were so proud of from home would have been below average here even without your size and definition reduction. Average erections here are 7–9in, compared to your world’s 5.5–6in, and slightly thicker. Thick beards and body hair are universal among this world’s men.
Women are similar in height to our world, but again have some slight enhancements that would top tier of our world’s women—slightly plumper lips, naturally trim waists, and slightly wider hips. Breasts sizes are an average of 1–2 cup sizes larger than home. Essentially, every man or women on this planet you found yourself on would be a 9 or a 10 if someone were rating them back home. Libidos are slightly elevated, but not so far as to be out of place on our world. Men and women each may be attracted to any of the other genders, but tend slightly to prefer each other. Same-sex relationships are rare, but not unheard of.
He-femmes such as your new self and she-men like your girlfriend are more unusual from your perspective. Their sex organs produce the expected hormones (that is to say your ovaries are producing estrogen and your girlfriend’s testicles are pumping her full of testosterone) but the mixed chromosomal arrangement leads those hormones to different effects. She-men have significantly larger genitalia than even this world’s men and larger breasts than its women; they have no body hair except a very large, dense bush of coarse pubes. Their testosterone makes them more muscular than typical for women on either world, but their musculature is usually smooth and feminine in appearance. Their muscle fiber is also more dense, making them much stronger than they would appear. Reading this, you suddenly understood how your girlfriend was able to toss you around. Memories of her manhandling you onto the counter and the coffee table and ravaging you prompted a twinge in your pussy.
He-femme physiology is generally male-patterned, with subtle differences such as you saw in yourself earlier: wider hips to accommodate birthing; larger, more sensitive nipples and some slight breast tissue; overall a layer of fat distribution that you would think of as womanly; higher erogenous skin sensitivity; and slightly smaller musculature than you’re used to and, conversely to she-men, he-femme muscle fibers are slightly less dense than normal, making even larger appearing muscles weaker than expected. At baseline, an average he-femme and an average she-man would be equivalent in strength, but the hormones have an additional effect.
To manage the discordance between the body type and the sex-hormones, he-femmes and she-men go through hormonal cycles. He-femmes have a period of “heat” during which their bodies are flooded with additional hormones. Hormonal action further relaxes and inhibits the efficiency of muscle fibers, making he-femmes weaker during this part of the cycle and more flexible. A he-femme in heat can be quite acrobatic during sex, more resilient to their partner’s dominant tendencies, and able to accommodate the penetration of extremely large objects. Their proto-pec-breasts, hips, and ass swell slightly, and they have been know to give milk, even when not pregnant. A he-femme in heat is extremely horny and submissive. If pregnancy is not achieved during heat, he-femmes will experience what you would commonly know as a period. Symptoms can vary from mild to extremely severe, with menstrual bleeding, cramps, bloating, irrational flights of emotion, and unusual cravings.
She-men similarly experience a hormonal cycle known as ‘rut’ during which higher hormonal production can produce significant personality changes, generally significantly increased expressions of dominance. Other physical effects of the she-man’s cycle include additional body hair growth, generally a small treasure trail; as well as muscle growth and significant enlargement of the genitals.
Both of these genders have a baseline libido that would be remarkably high in our world, but it increases significantly during their heat or rut cycle. On-cycle individuals also emit pheromones that can significantly increase the libido of those of any gender in intimate contact with them or who are often nearby over an extended amount of time. This effect is especially pronounced among oppositely-gendered she-men/he-femme pairings.
These cycles can occur roughly monthly, but are also influenced by external factors. Sexually-charged activities or emotionally-distressing situations that evoke an aggressive response in a she-man can trigger a hormonal surge that begins a rut cycle early. Similarly, a he-femme may go into heat when unusually aroused, sad, or angry. He-femmes and she-men in close contact generally sync to each other’s cycle. For this reason it it not common for she-men to live together—a group of she-men rutting in the same place can provoke violent interactions. He-femmes and she-men may partner with any of the other genders, except that same-sex she-men pairings are incompatible for reasons discussed above. He-femmes and she-men have a fairly strong preference for each other, but same-sex he-femme pairings are also common. On-cycle pairing between these two genders are almost certain to result in pregnancy, and anyone becoming impregnated by a she-man’s sperm is unusually likely to develop a multiple-pregnancy.
The physiological and psychological effects of the hormonal cycle in these genders are generally temporary, reverting at the end of the cycle; however individuals that repeatedly cycle early my develop more permanent and more pronounced effects.
Hims and herms have respectively masculine-patterned and feminine-patterned body types with both types of genitals. Penises are smaller, typically no more than 3in erect; and the arrangement of genitals varies: some have a vagina below the penis, and some have the vagina on top. Testicles are smaller, and may be contained within a scrotum like a man’s or may be entirely internal. Hims are shorter than Men; Herms’ breasts are smaller than Women, and their bodies often, but not always, have a slightly androgynous appearance. Libidos are high, and hims/hers are the most versatile sexually, pairing well with any gender. They view sex casually and are unlikely to have long term partners. Him/him, herm/herm, & him/herm sex is almost as common as a polite greeting. Hims or herms with the penis located under the vagina frequently penetrate themselves, and self-impregnation is common, although it rarely comes to term.
Nulls are distinct, but are very androgynous in appearance, and null-hes and null-shes are generally indistinguishable. With no genitalia or sex-hormone producing organs, nulls have almost no sex drive, except they become very aroused when exposed to the pheromones of any of the other genders. All nulls have very long tongues and extremely sensitive mouths, tongues, lips, & throats; as well as sensitive and self-lubricating anuses. If they are aroused, null-hes strongly prefer being penetrated anally and null-shes strongly prefer performing oral sex. Both are capable of becoming pregnant if sperm is introduced to either orifice, and two nulls may reproduce with each other through a process where DNA is exchanged between them by intertwining their tongues.
Getting to the end of your reading, you realize you’ve been absentmindedly tweaking your nipples and stroking your clit as you took all this sexy information in. You still have several hours before your girlfriend comes home so you decide to…