Although Emmie is a distant cousin to Essey, neither of them realized they'd be living right next door one day! Emmie owns the dairy farm next to the bakery and weaving studio that Essey and Zari inhabit, and Emmie's nikyak, Fluffers, is constantly getting into trouble about the place or begging for fresh baked treats.
Emmie is very happy to live so close to woolies that she is comfortable with, as she tends to be shy; moving into a new community was a difficult prospect for her, so having Essey and Zari around helped her integrate so much faster! She also won't turn down fresh baked bread, and is frequently happy to offer aged cheeses and dairy products in barter for Essey and Zari's goods.
Essey can't imagine what her life would be like without Zari, and would walk through fire for her friend. Although they had very different upbringings, Zari is all of the family that Essey has and she is very protective. While Zari is very tough, physically and mentally, Essey is always keeping an eye on her and ready to step in with a quick word or distraction when she thinks Zari needs to take a moment for herself.
Opal doesn't remember her life before Maia was in it, and their worlds are inextricably linked together. Maia's outgoing nature is perfect to help Opal come out of her shell and meet people that she never would have known, and her matter of fact nature brings Opal into the real world, reminding her that there are things more important than just what's inside books.
While Opal is a passive, nonconfrontational pouflon, there is simply no doubt that if Maia needed her, she would brave fire and flood to be there for her friend.
Opal is Maia's best friend in the world. They have very different personalities, but they complement each other (and enable each other). While Opal stays in Riddlelock, Maia roams far and wide, bringing back gifts of teas and maps and astronomy books. Maia would fight at the drop of a hat if someone threatened Opal.