The tragic brothers and lovers of Chapter 2: The Place Inside the Blizzard.
Hode commits suicide when he learns they can no longer be together, and Getheren is run out of town. Getheren's travel across the glacier foreshadows Ai and Estraven's travel across the Ice. The story also hints at the revelation of Estraven and Arek's relationship.
That's two foreshadowings for the price of one. Not bad!
In Chapter 4: The Nineteenth Day, Berosty asks for a foretelling of when he will die. He's told the 19th day. His lover, Herbor, attempts another foretelling of the same question and is told that Berosty will live longer than Herbor. Seems hunky-dory to us, but Berosty is enraged that Herbor didn't get a more specific answer. He kills his lover, and this causes him to go mad and commit suicide on, yep, the 19th day of the month.
Moral of the story: prophecies are dangerous, yo. The story is located right before Chapter 5, when Ai goes to the Fastness to receive his own prophecy. What a coincidence.
Chapter 7: The Question of Sex is written by an Ekumen Investigator. It is a reflection on Gethenian sexuality and the possible impacts it has on their society. The way Chapter 7 is written lets us know Le Guin is a born and bred anthropologist.
Meshe is the founder of the Yomeshta religion, which is practiced in Orgoreyn but not Karhide. We get two different stories about Meshe. The first comes from Goss. He says Meshe was the weaver for a foretelling meant to answer the question, "What is the meaning of life?" He started his own religion while everyone else involved either went insane or was killed. So, he seems have gotten the better deal.
We next meet Meshe in Chapter 12: On Time and Darkness. This chapter tells a couple stories revolving around Meshe's ability to know everything past, present, and future, an omniscience usually reserved for the big hombre in the sky. Basically, Meshe is a Jesus-type figure for the Gethen world.
We also learn how his religion differs from Handdara in Chapter 12, but perhaps that's a discussion best left for the "Symbols, Imagery, Allegory" section.
We hear this trio's tale in Chapter 9: Estraven the Traitor.
Therem of Stok and Arek of Estre come from two warring domains. Although enemies, they have a West Side Story moment and fall in love. The honeymoon phase doesn't last though, since Arek is killed by Therem's countrymen—again, just like West Side Story but with blood and without jazzy knife fights.
Meanwhile, Therem runs off to have their lovechild, eventually bringing the baby to Arek's father to be raised. The child grows up to be Therem of Estre, and when the two Therems are reunited, they bring peace to the land.
Whew. The story draws parallels to the current conflict between Karhide and Orgoreyn. It also helps establish the themes of love and communication as a means to bring people together and how the connecting of people leads to peace between countries (hinting at the novel's ending).
Also, notice how the names Arek and Estraven appear in the main story as well? Hint hint, nudge nudge, wink wink.
In Chapter 17: An Orgota Creation Myth, we hear the story of how Edondurath is the mythical father of the Gethenian people. An androgynous Adam, if you will. The difference is Adam had a small, if ill-advised, snack while Edondurath viciously murdered every living person save one and built a house from their flesh. Apple, house of flesh, eh, same basic idea we suppose.