There are a couple of days at the edge of each month where the old sign is weak enough and the new sign just gaining enough strength that both signs influence the person born on those days. These were relatively rare but far from unheard of, and live between the domains of the main signs. That rarity was before Earth gradually shifted out of the alignment with the stars that originally determined the zodiac signs. Some people say the signs shifted with the stars rather than the dates; others say the seasons matter more so the dates still determine the sign. Both are right, but it depends on the individual. Some naturally gravitate more toward the sign of the stars above them, others toward the sign of their season, and some are equally influenced by both. Thus the presence and prevalence of cusp individuals has steadily risen.
Aries+Taurus=Tarius (L~M~H) [f2M] Diurnal, Trade: Wool and Milk
Basically Satyr-like Minotaurs, but a bit more human in the face, and mostly covered in black wool save their face and breasts, with horns and ears comparable to sheep, goats, and/or buffalo depending on the individual and their age. They stop ageing in their mid-teens to early 20s until age 50, at which point they turn male and their wool turns white and they resume normal aging, still not all live to 50 so there is a hi female to male ratio. Every Tarius under 50 is a female and, despite being humanoid, aren’t yet capable of human speech or complex thought and are treated as livestock even by their own mates. However, they are especially precious livestock, too precious to let anyone eat, because they will develop higher brain functions with age and by 50 will become fully intelligent males with only fuzzy memory of their first 40 years of life, and yet all language and concepts they were exposed to absorbed into useful knowledge.
The Tarius tribe are nomadic hunter gatherers who mostly set up camp near the roads between cities, traveling and living in relatively modern vehicular homes (this can vary depending who they trade will, Tarius who trade with low-techs will be a bit more old school, maybe just a step up from covered wagons, and futuristic if they trade with hi-techs). The Tarius females are bred as dairy cow wool sheep; the males need to ingest their milk daily to survive and tend to suffer up to full body baldness around age 90 and so need the wool to keep warm. The resulting society is something like a friendly, fiercely protective biker gang of strong elders (remember that at 50 they still have the strength of a 20 year old, so they can live strong for longer than humans, and have a lot of muscle by default) with a lot of happily ditsy girlfriends.
Wild Tarius tend to stay away from big cities and any lost and found Tarius are kept until mature, returned to their elders if they can be positively identified. Visitors form earth will find they de-aged, those over 50 will become a 30 to 50 year younger male and those 20 or younger will find themselves a female the same age (maybe a year or two younger). Visitors between 20 and 50 will become a female between 20 and 1 year old at complete random.
Taurus+Gemini=Taurmini (M~H) [M&f] Cathemeral, Trade: Tech(chemical)
Basically Minotaurs, but great ape instead of bull, still have bull horns and tails though, and also they come in twos. Every male and female Taurmini is conjoined together by the ends of their black and white striped tails, both are considered half of a whole Gemini, visitors will suddenly gain an opposite gender twin (and if a Taurmini’s tail is cut both the male and the female half will die). However, both halves share a single high-functioning brain and minds. Technically this brain is stored in the male half, but visiting females will remain the only one in control of this thinking side, and all Taurmini experience the senses through and control the voluntary functions of both halves anyway so unless the male head is damaged it doesn't matter where the brain technically is.
The Taurmini female sides are capable of varying the milk they produce through meditation in any way that won't harm them from the inside out, and can trigger relatively high levels of production at any time. These capabilities resides in the female side's brain where the higher-human thought would have been in a full Gemini. As a result, this society is only half as high tech as the Gemini, except when it comes to chemistry where almost no one can compare. They're comfortable living without near as many moving machines since they have high levels of strength and endurance.
Gemini+Cancer=Gemcer (H) [M2F & M2F] Aquatic, Trade: Tech(esp. designed in or for water)
The Gemcer tribe are large gray lumpy amphibious four armed mutants a little monkey-like around the ears, feet, and tail that like to live along the shores near cities. Gemcer come in twos, and by that I mean every Gemcer has a psychological inability to be separated from their twin by too much spacetime, both are considered half of a whole Gemcer, visitors will suddenly gain an opposite gender twin, and if a Gemcer is cut off from their twin so they can't sense each other both will panic, hyperventilate, and die of a burst heart within about an hour (or longer if they've practiced enough meditation but it'll be all they can do to just keep living some extra time, not thinking about anything besides getting back with their twin or even drinking before dying of thirst).
Gemcer twins are both male by default, and connected by a tail like full Gemini at birth. The Gemcer tribe has the amazing ability to regenerate lost body parts, including the tail so cutting it doesn't kill them, with the exception of male bits; if those are removed it triggers a change in that half of the Gemcer turning it female. In the wild the Gemcer tribe is violent, but using their minds together to outsmart rivals as much as out brawn them. Bull males will try to “De-man” revile males and then claim them as new mate when they turn female, but more often than not will lose one of their twin's male bits in the process, so as wild Gemcer pairs get older they get more likely to have settled as male and female with an equal pair for their mates, or even to have been completely dominated.
Some Gemcer wear cybernetic enchantments they make themselves; they have the minds for it, and aren't opposed to working some time with Gemini and Aquarius to get access to more tech. And some move into the cities, more as equals than as servants though they do face prejudices, and some reinforce the prejudices by continuing (though underhandedly) to try to de-man and dominate other Gemcer and Cancer living there. It's still an easier life in the city, not having to be nearly as on-guard all the time, so Cyber Gemcer in the cities consider themselves better off than wild Gemcers. Most Visitors choose to be upgraded to cyber Gemcers, and can choose whether each half will be turned female or remain male during the operation free of charge.
Cancer +Leo=Cerlo (L~H) [M=F 2 F=M 2 M=F 2...] Aquatic, Trade: None
The Cerlo tribe are large, water-and-land-dwelling, four armed anthros or Ware-beasts that have components of several different predators (croc/gator, crab, snapping turtle, water moccasin, etc.) that like to live in the rivers or swamps. Visitors will be happy to know that you will retain your original technical sex with this race, however it's such a gender-fluid race that it's more useful to think of gender characteristics as belonging to number-of-transforms than anything else. Both sexes have lactating breasts, the female ovaries grow in the same place and way as male testicles so both sexes have balls, and female Cerlo reproductive organs are not unlike female Hyenas: instead of a slit, female Cerlo have a long fleshy tube they use to suck the baby juice out of their mates (so, visually, both sexes have dicks, though it is possible to tell them apart on inspection since the female dick is more hollow). Both male and female Cerlo faces look pretty androgenic. The Cerlo tribe has the amazing ability to regenerate lost body parts, with a huge caveat about the crotch bits: if those are removed it triggers a change in the Cerlo turning it to the opposite technical sex and increasing their dominance. Cerlo who have never had this trigger are the most submissive, least muscular, and have the smallest crotch bits, fastest and longest growing hair spines, and highest singing voices. With each regrowth of opposite sex bits they get more aggressive, larger in muscle and bits size, deeper in voice, and slower in hair spine growth (though whether they want to cut the spines they already had is a separate issue) eventually becoming unable to grow new hair.
What keeps wild Cerlo from intentionally triggering this change repeatedly is the pain associated. The first one is near as bad as giving birth, and each one after feels significantly worse than the one before it. In the wild, the Cerlo tribe is violent and animalistic bottom feeders, bull males will “De-man” revile males intending to claim them as new mates when they turn female, and bull females will do the same to rival females for the same reason. Their aim is often to pick rivals they think have had at least two fewer sex changes than themselves so after the change they'll still be dominant, and as a result sometimes the best strategy is to fake the opposite level of dominance (trying to act aggressive so not to be chosen as a target if you're actually more submissive, or trying to act submissive to trick them into trying to dominate you and then dominating them after they change you if you're actually more aggressive). Eventually Cerlos who have been through very many sex changes will reach a point where they just try to dominate all rivals regardless of submissiveness, their level of aggression outweighing any fear of being beaten, and there's a point some number of sex changes after that where they will start intentionally changing themselves, repeatedly pushing through the pain in attempt to get stronger. If nothing else kills them by that point, they'll probably kill themselves by pushing to an unsustainable level of growth. If they've witnessed another Cerlo die that way they're far less likely to over do it themselves, but there are rarely witnesses since these Cerlos find somewhere secluded so they won't be taken advantage of while in pain. It is technically also possible to be dominated enough times to reach an unsustainable level, but the more times one has gone through that change the more difficult and less likely it is to dominate them again.
A small number of Cerlo wear cybernetics enchanted by the Gemini and Aquarius tribes. Cyber Cerlo are mostly workers and servants in the cities, some cities keep Cerlo as pets, and if they haven't lost too much submissiveness they consider themselves better off than wild Cerlo, (usually) free from risk of being violently dominated. Very aggressive Cerlo would feel like slaves or prisoners in cities and seek every means of escape, and are usually released for being more trouble than they're worth except in the case of sometimes illegal "dog-fighters", legal arenas where they agreed to contracts before being dominated enough times to start going native, and at least one cruel circus. Visitors can choose to be upgraded to cyber Cealo, and can choose to have one sex change with enough pain killers to make it painless during the operation free of charge if they want to shed one layer of submissiveness (remember that without that they're as weak and submissive as possible, letting everyone without exception walk all over them and never pushing for their own will; also remembering that this change will make the visitor the OPPOSITE sex they were on Earth and to keep their original sex they'd either have to be that submissive or go through a second, very painful change).
Leo+Virgo=Liro (M) [Fm] Cathemeral, Trade: Dense Milk
The Liro tribe are a winged anthro or Ware-beast like all masculine female race smaller than Leo but larger than Virgo. They have components of several different predators, ocelot, coyote, great owl, wild dog, etc. Visitors be warned, if you have become a Virgo and are post pubescent you are already pregnant with a litter. Liro give birth to live young; all unfertilized fetuses will be male, sex is only needed to create another female. Male Liro are submissive mindless drones just like their mother but less muscular, with longer manes, longer legs, higher singing voices, and lactating breasts, looking and sounding female by human standards; males still have balls and a dick, all retractable. Drones don’t have wills of their own and can only eat the dense milk their mothers and brothers lactate (evaporated, sweetened condensed milk is the closest approximate on Earth, but Liro dense milk is more flavorful and healthier). Every Liro is a technically female king: aggressive, muscular, masculine faced sometimes including beards and long body fur, and have reproductive organs not unlike female Hyenas, instead of a slit female Liro have a long fleshy tube they use to suck the baby-girl juice out of their mate's drones and a couple of balls of their own underneath; females still have breasts of their own spread over large pecs. The Liro tribe live in forest canopies and hunt for their food. They're capable of much higher tech than they care for, pouring their brilliance into creature comforts instead of high tech or high art (think hunter lodges taken to royal extremes). The Liro keep connections better than most wild tribes, but tend to spend too much time competing for fun, hunting for sport, and lounging around to be as connected as the Virgo. They can handle the Scorpio but would rather not.
Virgo+Libra=Vligra (M) [Ff = Mm] Diurnal, Trade: "Golden" Eggs
This tribe looks like feather-winged "angels" (sometimes "fallen") with bright colored hair, on the short side of human heights. Vligra start life genderless and gray feathered; we don’t know how it works but if the Libras good it will turn white feathered and female, but if it’s bad it will become black and male. Visitors, no matter how good or bad they were on Earth, will start gray and will be judged male or female by their actions on Zodiac. The Vligra tribe has a wild village in the tree in the forest but the vast majority of Vligra build roosts of their own near cities of other tribes.
Female Vligra outnumber the males and females lay eggs twice or more a day. Unfertilized Vligra eggs still hatch, they just develop as mindless drones; sex is only needed to create another roost. Drones look like smaller versions of the one that birthed it, even changing to grey or black or back to white as their mother does; drones don’t have wills of their own and can only eat whatever their mothers lactate instead of milk (a closely guarded secret, especially since this "lactation" doesn't end if the Vligra goes bad and becomes male with drones). Every Vligra can be the head of a whole host or legion if they are just good enough for long enough to birth some, and they like to live as such. They are capable of being a hi-tech race, but they tend to become so obsessed with morality that their brilliance is spent on philanthropy, philosophy, law, and religion or anti-religion (depending on whether the individual sees the good or the bad in religion), leaving them with only lower-modern tech with some exceptions who see striving for high technology as a part of goodness or some who would rather be male for a while anyway if "playing god" is bad. (There are very few who would rather be male all the time than ever spend some time gaining drones, though, so even the worst villains take breaks to be heroes for long enough to build forces.)
When the drones are female (because their mother is) they also lay eggs, but their eggs never develop into more than food. Vligra drone eggs are a delicacy on Zodiac, flavorful, sweet, and shining gold.
Libra+Scorpio=Scabpriol (L?) [M&F] Nocturnal, Trade: Ha! Good luck!
Four legged, four arm-winged, black feathered, masculine demons with bright red hair and powerful talon claws at the end of every limb, as well as sharp, venomous demon tail dicks. Visitors beware, wild Scabpriol will eat members of any tribe including their own, and all the natives are wild. They can hold a civilized conversation, but they'd only do so as part of a trap. To reproduce, a victor will pierce his tail through his victim's navel to plant his seed in the victim's womb (they're all technically hermaphrodites, they just never show their feminine side except as part of a trap). The young eat their "mother"s from the inside out. Visitors are recommended to get fixed. We don’t know really anything else about them; no survivors have managed to learn more than that.
Visitors can but don't have to go bad, however. They start off grey feathered and androgynous (though capable of both sexes), and can spin silk from their nipples. If their actions on Zodiac are good, their feathers will turn white, they'll grow more feminine, if they haven't been fixed they'll start laying small Libra eggs, and they'll start making milk instead of silk. They never naturally lose the tails, though, and their children are always fatal for the child bearer. Castration is an option.
Scorpio+Sagittarius=Scagittorus (M?) [M&F] Cathemeral, Trade: Silk
Scags are human upper bodies in the place of giant female scorpion heads; the giant scorpion bodies have web spinning ankles and acid spraying tails that double as male genitalia that plant deadly births like Scorpios, and visitors are recommended to get fixed. The color of the exoskeleton loosely matches the human skin, hair, and personality, and for visitors the human portion is what they had on Earth. They do dress nice, adopting and progressing the prevalent styles around where they happen to be when they make their silk clothes. Scags are omnivorous without exception. However, they can be befriended, hired as hunters and farmers, and even ridden as long as the rider doesn't let the Scag get too hungry or angry with them. One always has the feeling a Scag knows and is planning a lot more than they let on, though...
Sagittarius+Capricorn=Caprittariuns (L) [M2F] Aquatic, Trade: Oil
Female Caprittariuns are huge wale sized orca mermaids that can swallow a man whole. Their young however look like teen sized male Sagittarius (centaurs). In exchange for looking after their young, the Sagittarius farmers are given some of the valuable oils the Caprittariuns’ bodies produce. The male Caprittariuns will grow up on land and return to the coast every mating season. Only the biggest male is allowed to mate, and he will mate with every female on the beach, but the act of mating will trigger the change from male to female, the male will leave with the females out to sea and by next mating season he will be fully female and mate with the next biggest male. Caprittariuns don’t have any real tech and are mostly thought of as predators by other aquatic races, however they've been known to be playful and even helpful if their trust is gained (unlike full Capricorns who may also be befriend-able but far more rarely if ever).
Capricorn+Aquarius=Acaprius (M) [F2M] Aquatic, Trade: Oil
To say the Acaprius start female and turns male is a bit misleading. They start life genderless but female looking Aries, this Aries has a womb without eggs. In exchange for looking after their young, the Aries nomads are given some of the valuable oils the Acaprius’ bodies produce. The young will grow up on land and starting at the age twenty will return to the coast every mating season.
Elder Acaprius are huge, almost wale-sized, "seal men" that can swallow a man in two bites. They both look male but one of them is female and will lay eggs in the young Acaprius with her ovipositor and the other will fertilize. Only the biggest female-looking Aries are allowed to mate (no actual Aries will want to, only the ones that are actually young Acaprius), up to one for every seal-man couple in the water (they may refuse smaller ones even if it leaves them without a mate this season, though in that case there will be a fight over the larger ones). The act of mating will trigger the change from faux-female to seal-man, gaining a binary sex, leaving with the seal-men out to sea and by next mating season they will be fully seal-man and mate with the next biggest faux-female. Visitors will start as a faux-female Aries and will become a seal-man of their former gender. Acapruis have roughly modern technology in underwater towns.
Aquarius+Pisces=Aquipsces (M) [F&M = M&F] Aquatic, Trade: Ink
The Aquipsces are squid men and women with tentacle arms and legs, and if you think you see them kissing they are really doing something else. See what looks like a mouth tongue are a pussy and dick, their mouth is down between their tentacles so if you see them shove a fish up there they are just eating. Aquipsces also have two ink sacks that look like boobs or balls (if balls then they're big ones with a large false phallus to match, hold some of the ink, and spurt it instead of nipples). Pisces live in and around the underwater city, they are fishermen of a sort and supply the seafood market of Zodiac. Since they're all herms anyway there's no sex-change business, but Aquarius instincts make them generally prefer devil's threesomes. Visitors will have the appearance of their former gender. The Aquipsces tribe lives in the hi-tech under water city, sometimes as elites and sometimes as simple fishers but mostly as artists.
Pisces+Aries=Pacies (L) [F&M] Aquatic, Trade: Choral (and sometimes water colors)
The Pacies are octopus girls with tentacle legs and no arms, and if you think you see two kissing they are really doing something else. See what looks like a mouth tong are a pussy and dick, their mouth is down between their tentacles so if you see them shove a fish up there don’t worry they are just eating. Pacies also have two ink sacks that look like boobs, but their ink is much more watery than full Pisces. For Pacies these are always coral octopi, and unlike Earth's coral octopi they actually spawn coral in a way that looks just like Aries growing wool covering most of their bodies save their "face" and breasts. (The coral polyps are technically separate animals, but they're too small and simple to count as drones, much less separate will powers.)
They start aging very slowly in their mid-teens to early 20s until age 50, at which point they lose their ability to produce ink or spawn colorful coral (they continue to spawn white coral, though progressively less of it) and and they resume normal aging and grow ever more masculine in appearance, still not all live to 50 so there is a hi feminine to masculine ratio. Visitors from Earth will find they've de-aged, but not as drastically as a full Aries and only half as often at random. Also, gender doesn't matter so much to them; it's trivial to flatten or fake their ink-breasts and they're reproductively all the same.
Pacies live nomadically in and around the underwater cities, camping in the seafloor fields between. They do fish but are much more like gypsies selling trinkets and secrets and dancing or story telling for alms. Some would have you believe their soothsayers and spell casters are only stereotypes or myths, but once in a while you may find one who has truly learned to understand and/or influence the coral polyps going and coming and you'd be wise not to dismiss them as entirely a sham.