I feel like there isn't a lot on the Dioskouroi in pagan spaces, so I hope to get some people interested in them!
Relief from the Sparta Museum (source)
Dioskouroi is theorized to come from dios kouroi, meaning the sons of Zeus.
According to the most well-known version of their story, the Dioskouroi are divine sons of Zeus and the mortal Leda. Leda gave birth to them in an egg after laying with Zeus in his swan form, from which they emerged as youths.The Disokouroi are known in Greek as Kastor and Polydeukes, or in Latin as Castor and Pollux; the constellation Gemini.
They were popular in Sparta because they were said to have been born there.They are the gods of what is known as St. Elmo’s fire, which is a kind of electric discharge that shows up around the masthead and rigging of a ship and foretells the end of a storm. They are also the gods of horsemanship and protecting guests/travelers. Sailors prayed to the twins for sea related problems. Karl Kerenyi lists them as gods of war as well.
There is not much known about their mortal lives, but they were said to have participated in many adventures such as sailing with Jason (Iason) and the Argonauts. They were turned to gods for their goodwill, alternating between Olympos and our world. Some myths say that Polydeukes is a son of Zeus while Kastor was the son of a mortal, but Polydeukes’ sorrow upon Kastor’s murder led to a deal with Zeus that led to their alternating trips between earth and Hades. This likely references how the constellation is only visible for half of the year.
Nemesis and the Dioskouroi in Hades, C. 4th century BCE
They are usually shown wearing the same clothes but posed slightly differently, often wearing pointed hats called piloi, near horses and armed with spears or shields. The piloi sometimes had stars above them. Alternately, sometimes the twins are depicted wearing flat and wide travelers’ hats. Sometimes they were depicted as parallel bars known as the dokana, which were essential to the foundation of their worship. They are always depicted and worshiped together "...as separate yet connected entities that are of equal force (Gaifman, 300)."
Piloi on the left on a coin from 2nd century BCE (source)
They are often represented with snakes (since they were once mortals, and snakes are cthonic creatures). They were often worshiped using lidded amphorai, as seen in the first picture in this post.
M. Gaifman, Aniconism in Greek Antiquity
K. Kerenyi, The Gods of the Greeks