Updated: Jul 19, 2021
Strong, mighty Hephaistos, bearing splendid light,
Unwearied fire, with flaming torrents bright:
Strong-handed, deathless, and of art divine,
Pure element, a portion of the world is thine:
All-taming artist, all-diffusive power,
'Tis thine, supreme, all substance to devour:
Aether, sun, moon, and stars, light pure and clear,
For these thy lucid arts to humanity appear.
To thee all dwellings, cities, peoples belong,
Diffused through mortal bodies, rich and strong.
Hear, blessed power, to holy rites incline,
And all propitious on the incense shine:
Auppress the rage of fire's unwearied frame,
And still preserve our nature's vital flame!
--Orphic Hymn to Hephaistos, ca. 1st century B.C.E.
Hephaistos, Sam & Steph Braithwaite, 2014 for Hero's Journey
Hephaistos is the Greek god of craftspeople, invention, and technology, three concepts that are bound up together and once meant different (but still adjacent) things than they do today. Also the god of fire, largely because as a creator he was associated with the smithing of metals which requires a forge, the Romans later leaned into that by making him Vulcanus, the patron god of the Sicilian volcano Aetna (modern-day Mt. Etna), which conveniently gave them someone to give offerings to so that it would stop erupting and dumping super-heated ash on everyone's homes. But even in Italy he remains primarily a crafter god, because that's what's most important about him and it never wavers: he is the source from which all the gods' (and many Heroes') divinely magnificent items come.
In fact, if you can name a famous object in Greek mythology, odds are you can find at least someone claiming Hephaistos made it; even objects that were added in later stories often get this treatment, because if you want to impress your audience with how cool a sword is, it never hurts to claim it was created by the ultimate master craftsman himself. Among other famous items created by him we have the chains that bind Prometheus; the arrows of the twin gods Apollo and Artemis; the thunderbolts of Zeus; the Aegis of Athena, which she later lends to Zeus as well; the armor of Akhilles; the knife of Perseus; the armor and quiver of Herakles; ALL the palaces the gods live in and at least half their chariots; about seven distinct kinds of automatons that put any science fiction story to shape; and literally a bunch more besides. If something in Greek mythology needs to be so badass you can do super feats with it, it needs Hephaistos on the job (or, occasionally, he can supervise his assistants the Kyklopes, who also make some pretty rad stuff).
Making armor, being sexy: the forge life
Hephaistos is also a very visibly disabled god, which is interesting for a number of reasons (and affects nearly all of his myths). He was born with a twisted or withered foot, described differently depending on the tale; some modern-day scholars believe that this is likely to be a representation of the fact that ancient smiths made bronze by adding arsenic to copper and unfortunately as a result often walked with a limp as years of breathing in low doses of poison damaged the nerves and withered the muscles. If Hephaistos is the god of crafters and tradespeople, then he shares their experiences and represents them, and several of his inventions, such as the walking tripods that circulate around and serve food to the gods so they don't have to get up, are things we might recognize in the modern day as accessibility tools.
But Greek mythology (and a lot of ancient Greek philosophy and religion besides) is very hung up on the idea of physical perfection, which comes into play for Hephaistos with nasty results. Because the Greek concept of teleos or perfect physical beauty was tied to the idea of becoming your most advanced self, naturally the opposite concept - that being imperfect was a sign of flawed character - became a problem, especially since, like every other society in history, the Greeks had their own socially accepted idea of what beauty meant and not everyone could fit into it, especially including those with physically visible disabilities. So Hephaistos is simultaneously a noble and powerful deity who is absolutely vital to human civilization, and also at the same time a figure that is inexplicably treated with derision and contempt by the other gods.
So the myths of Hephaistos' exploits often revolve around this contradiction, with his fellow deities rejecting him for his disability even as they desperately need and want the incredible things he makes for them. It's especially easy to see this in action with the story of his birth... or at least, with one of the stories of his birth, because there are actually two!
Thetis, you are not going to BELIEVE when I tell you about my parents
In the most common version of the myth, Hera is infuriated by her husband Zeus giving birth to Athena by himself (or, more accurately, with Metis, whom everyone knows is still inside Zeus due to his unfortunate cannibalism habit), which insults her position as goddess of motherhood and family. In return, she refuses to sleep with Zeus anymore, instead deciding to parthenogenically receive and give birth to a son all by herself: Hephaistos. (There is a version where Hephaistos is Zeus' son as well as Hera's, but this is a lot less common; most of the time, he's mother's little boy only.) Once we get to the god's birth, however, things start to get weird.
In some versions of the story, Hephaistos is born with his disability. In these versions, Hera usually sees that her son is disabled and flings him off of Olympos in an attempt to prevent anyone from finding out that she bore a less than perfect child, and Hephaisto falls all the way to earth, where he is rescued by Thetis and raised by she and her fellow sea nymphai. This is a pretty straight-forward cautionary tale about not deciding to flout the natural order of things (Hera having a child without her husband's involvement) and about disability as a physical sign of flaw or corruption (because Hera had her child "incorrectly", that child is permanently flawed), and not very much fun since it's dripping in gender essentialism and disdain for disabled people, but those are the breaks sometimes when we study ancient cultures.
In another version of the story, however, Hephaistos is born as physically perfect as any of the other gods and grows into a child or young man before being cast off of Olympos. In that version, Hera attempts to kill Herakles (as she does) and in a fury Zeus hangs her from the roof of the heavens in chains, and when Hephaistos tries to rescue his mother, it is Zeus who hurls him off the mountain, and the force of smashing into the earth breaks his leg and gives him his permanent limp. This version has considerably different implications, carrying on the rivalry between Hera and Zeus over the children they don't share (now with Herakles in opposition to Hephaistos) and implying that Zeus' reaction against Hephaistos is probably largely due to his anger that the kid is loyal to her rather than to him, or at least willing to question his authority.
If the ancient Greeks had had the word "yeet", they'd have used it a lot
(Hilariously, Homer repeats both these versions, literally out of Hephaistos' mouth, while Pseudo-Apollodorus sticks with the Zeus-casting-Hephaistos-out version and the Homeric Hymns stick with the Hera-casting-Hephaistos-out version. So pick your poison, really. Probably arsenic.)
Either way, Hephaistos ends up on earth in foster care, which is frankly probably a lot safer for him while his massively powerful and completely impulse-control free parents are fighting. Most myths afterward agree that, angry about being exiled for something he cannot control, Hephaistos builds beautiful thrones for all the gods and has them shipped up to Olympos, but builds invisible chains into Hera's; as soon as she sits down, they snap into place and she is permanently trapped in the throne. (There's some argument even as early as the tenth century over whether this is a revision of the Zeus-chaining-Hera-up incident with Hephaistos now cast as the aggressor, but we can only guess!) Everyone understandably goes bananas - after all, everyone's tempers aside, Hera is essentially the heart of Olympos, wife of the king and mother or adopted mother to most of the gods, so no one is happy about her suffering.
So, as you do when there's an emergency, you find the drunkest guy who sounds confident and you send him out there to handle it. Dionysos (who may be sympathetic to Hephaistos as another divine child who almost didn't make it and had to prove to the gods he deserved to be allowed on Olympos) heads down to earth, gets Hephaistos roaring drunk with him, and conducts him up to Olympos, where the two of them give the gods the ultimatum that Hephaistos gets to stay and be properly honored with all the other gods, or Hera gets to stay in a chair for the rest of eternity. The gods relent, Hera is freed, Hephaistos gets his own house, and they spend the rest of time milking him for fancy jewelry and powerful weapons.
(If you're wondering, they did try a few other options first, including dragging Hephaistos upstairs sober to demand he fix this, to which he answered no, and sending famed Worst Diplomat Ever Ares and his kids to bother him on earth, after which they came back and said "sorry, boss, he wasn't scared of us, we've got nothing". Dionysos, one assumed, eventually volunteered either for the brownie points or because he finally got bored watching everyone be so bad at this.)
And the gods spake and said, "O Hephaistos and your tiny hat, can you just chill out a little please?" And Hephaistos and his tiny hat spake thus: "Absolutely not."
In Hero's Journey, all Greek Heroes have access to Arete, their ability to focus on and be truly excellent and exemplary in specific areas, but Hephaistos also grants additional Arete to his Heroes, giving them extra skill in the areas of Craft and Technology, giving them some of his mighty power over the realms of innovation, invention, and life-changing new technologies.
There are a LOT of other stories about Hephaistos, not least about his marriage to the goddess of love and beauty, Aphrodite, but we'll have to save those for later when we actually talk about her. In the meantime, marvel at the works of the greatest among divine smiths, and do not annoy him or he WILL give you a cursed amulet that turns all your descendants into snakes.