Today's question takes us back to the misty past of obscure Greek Titanes myth: North, East, South and West, the Greeks have Titans for each cardinal direction. Could you tell us about them? We totally can, and they're a pretty fun topic for exploration - let's hear about the four brothers of Kronos!
Ancient Greek descent lines always start with Khaos, the primordial tangle of unformed potential from which manifested the most ancient of the gods: the sky father Ouranos and the earth mother Gaia (among several others, but let's not get into the ocean and abyss branches of the family at the moment). Gaia and Ouranos both produce various children in a variety of ways (including together, with other partners, and just parthenogenically while they're doing their own thing), but among them are the first generation of Titanes, including the infamous Kronos. Kronos has several siblings, and among them are the four brothers that represent the poles or axes of the earth: Hyperion, primordial Titan of the sun, Iapetos, primordial god of mortality, Koios, primordial Titan of the stars, and Krios, primordial god of springtime and growth.
While we have a good general idea of the function and ideas behind these Titanes, we don't actually have a ton of information on their specifics; their worship primarily took place long ago, in the archaic periods of Greek religion, and very little sign of them has survived to be poked at by modern-day archaeologists. They appear in myth only twice in any majorly relevant way; the first is when, as Kronos' brothers and supporters, they reach out from their four corners of the earth to hold down Ouranos' limbs, allowing Kronos to castrate and defeat him with their help, and the second is when they again support Kronos in his battle to overcome the usurper Zeus, which they ultimately lose and are punished for by being cast into the pit of Tartaros.
Very cheerful stuff, as most early cosmological Greek mythology is, right? The four brothers, like a lot of other early Titanes, are more representational deities than personified ones; they represent ideas and concepts, and like their parents and siblings are part of the ancient Greek understanding of the structure and function of the universe. As the four directions, the symbolically cover and represent all of the known universe, and as the four pillars that were created by earth and heaven, they support it and contribute to its structure simply be existing. Not bad for some barely-remembered, highly cosmological dudes!
Most of what we know about each of the brothers is gleaned from the etymology of their names, the functions of their most closely related family members (especially their children), and the side mentions of them in various Greek sources, where they're usually used as poetic devices to describe something going on in a different story.
Hyperion is probably the most famous of the four (at least, he's the one who somehow managed to survive in a truly confusing form in a recent Hollywood movie), and while he's often characterized as a god of the sun, it's likely that he had a more ancient and less focused role as the god of all light, including the sun and various other sources of illumination. He was the pillar of the east, not coincidentally the direction from which the sun rises and lights the world; Diodorus Siculus claims that he was the first of the Titanes to understand the movements of the heavens, which is how he came to be the lord of the sun, moon, and stars, and why they were ever after subject to him. The same source also mentions his interest in the seasons that the movement of light created, so some scholars suggest that it's possible he was an ancient god of time's passage, or at least of calendars and measurement of time by light. Even his name is associated with light - literally, it means the one above, referring to the fact that light comes down from his lofty vantage point.
Hyperion's family members are all part of his light theme, which shouldn't surprise anyone who has ever looked at Greek mythological relationships more than casually. His wife is usually said to be Theia, his sister and a Titanid of light herself; her name means to see, and she was most likely envisioned as the goddess of clear air or atmosphere that allowed light to be seen (the opposite of smoke, fog, or other obscuring agents). One of the Homeric Hymns calls Hyperion's wife Euryphaessa, but since that name means brightly shining and Euryphaessa appears nowhere else in any Greek sources, most theories currently consider it a byname of Theia's, not a separate goddess. It's worth noticing that crochety old Hyginus claims that Hyperion's father was not Ouranos but Aether, the primordial Titan of the air, which similarly connects the ideas of light traveling through air to be seen.
The children of Hyperion reinforce his status as lord of light: they are Helios, the younger Titan of the sun, Selene, the Titanid of the moon, and Eos, Titanid of the dawn. (Pausanias also lists a god he only calls "Titan" as one of their children, but for the most part scholars are pretty sure he's just talking about Helios.) Since he is the original primordial god of light, it only makes sense for his children to be expressions of that light, appearing as the various celestial powers that shower illumination down on the world.
Compared to Hyperion and his (admittedly very tiny in the grand scheme of things) fame, Iapetos is one of the best-kept secrets of the original Titanes, which is probably mostly because we aren't entirely sure what he was about, exactly. His name means roughly he who pierces, and this, along with his close connection to all of humanity, has led some scholars to believe that he was a god of mortality, originally creating all mortal life and then overseeing the limits at which it must be ended. This role was very obviously taken on by the Moirai much later, but Homer's description of him sitting beside Kronos as a danger in the pit of Tartaros suggests that he was somewhat feared or ominous. Like his other three brothers (and Kronos too!), he was most likely in some way a primordial time god, in charge of things like the cycles of the natural order and the correct running of the universe, and since he has no obvious connection to time in a more cosmic sense like his siblings, it's not a huge leap to think he was instead concerned with time as it related to the mortals who were created from his line.
Iapetos is associated with humanity time and time again, both obviously and in a more roundabout, symbolic way (which is of course how Greek poets love to do). Most directly, he is the original ancestor of all living human beings in earth Greek myth; he is the father of Prometheus, who was in turn the father of Deukalion, the first naturally-born human being, who began the lines of humanity, all of which is notable since where the other Titanes of Iapetos generation are all about natural phenomena, Iapetos and his offspring apepar to be all about humanity and civilization instead. Iapetos' direct children bear this out - they are Prometheus and Epimetheus, the brothers who represent foresight and hindsight, ingenuity and cleverness alongside regret and mistakes, epitomizers of early Greek thought when it came to human qualities and sympathies. Both of them are highly involved in the creation of Pandora, the first human being, and the unleashing of the ailments of the mortal world through her. Iapetos is also the father of Atlas, who is not particularly connected to humanity but who is a major force among the Titanes and the guardian of the four brothers in particular. (In fact, we mostly know that Iapetos was the original pillar of the west because of the fact that Atlas takes that role over for him later... although some scholars would like to point out that since the sun sets in the west, it might also have something to do with Iapetos' status as the ender of things.)
While we know way less about him, Hesiod and Apollodorus also list a Titan named Menoitos as a son of Iapetos; all we know about him is that he was full of wrath and power but that Zeus struck him down for daring to challenge him, and that he now appears occasionally in accounts of the underworld Hades as the shepherd of the dead. His connection to dead people also reinforces the idea that Iapetos has something to do with lifespan, death, or otherwise ruining it for mortals.
Moving on, then we have Koios, who sometimes carries the grandiose titles "Axis of the Heavens" or "Lord of the Northern Pole". Strongly associated with the northern pole and the pole star (fun fact: it's called the pole and pole star in English from the word Polos, which is one of Koios' by-names - literally, we named poles after him), he's both an obvious shoo-in for the job of the northern pillar of the world, and also almost by default associated with the stars, since as the fixed point of the north he almost can't help but be read as a star or star-controller himself. Because of this connection to the stars, scholars theorize that he might also have been associated with oracles and prophecy, since the practice of reading omens in the stars was one established far back in the mists of Greek antiquity. His name is sometimes translated as meaning questioning one or curious one, which might also refer to the practice of seeking enlightenment from the heavens.
Like the other Titanes, Koios' children carry on his legacy and become ever more specialized and unique powers in his same area of influence. His offspring are two daughters, Leto and Asteria; Asteria is associated with stars, and her daughter, Hekate, with the night and moon, while Leto is the mother of the celestial twins Apollo and Artemis, who eventually take over the roles of sun and moon deities from the older Helios and Selene. In each case, Koios' connection to the heavens is apparent in his children; and his status as a possible god of oracles is also pretty obvious, with both Asteria and Hekate associated with prophetic knowledge and dreams, and Apollo eventually becoming the preeminent god of prophecy through his oracle at Delphi. Koios' wife, Phoibe, is also possible associated with both stars and forecasting the future from him, and her name was passed down to become a title for both Apollo and Artemis in various cults.
And then finally we come down to Krios, who is the most enigmatic and uncertain of the bunch (and that's saying something!). No one is quite sure what his name means, although the best guess available is that it means ram, which would make sense since his most common scholar-reconstructed association is with the seasons and especially springtime, when the constellation Aries (the ram in question) rises in the southern sky. Nonnus also refers to the idea of Krios as being associated with the constellation Aries, in a passage in which Helios (representing the sun) refers to Aries as the "navel of the universe" and claims that he begins springtime when he reaches him. Obviously, this leads to considering Krios the southern pillar, which makes sense since it's the only one left anyway.
Like the other Titans, Krios' children mostly reinforce the theories about him; one of his sons is Astraios, god of stars and inventor of astrology, which reinforces the idea of Krios as a star-god himself, and while another son, Perses, appears to be about war and destruction rather than having anything to do with stars himself, he married Asteria (the starry daughter of Koios) and was the father of the celestially adept Hekate. Pallas, a Titan god of warfare, seems like more of a stretch, but he was specifically associated with the late spring season in which the Greeks preferred to wage war, which again might connect him to his venerable father. Pallas is also notable for being the father of Nike, who goes on to be famously winged and ubiquitous in, like, all Greek sculpture ever.
And that is about what we know about these dudes. As described in the Titanomachy, the brothers were defeated, along with Kronos, and hurled into Tartaros by Zeus, where they are imprisoned in the dark pit forever (although occasionally Kronos is said by some writers to have been allowed to move to the Isles of the blessed - no such luck for these four, though). Because they're such ancient cosmological figures and represent the points of the universe, they have in the modern-day gained several small planetoids/moons/asteroids named after them, keeping their names alive, even if only for the astronomy nerds among us.
Incidentally, I know you didn't ask about them, but the four wives of these Titanes - Theia, Klymene, Phoibe, and Eurybia - are complementary universal powers in their own right. In one theory, since so many of the Titanides seem to have connections to oracular pronouncement, it's thought that all eight of these ancient beings did; the male Titanes might have been connected to the mystery oracles, revealers of the cosmic secrets of the world, while the female Titanides might have overseen the prophetic oracles, learners of things yet to come. Like everything else when it comes to these folks, though, it's all (fiercely argued-about and academically-backed-up) conjecture.