The first times we hear Sarima mentioned, it's in rather negative terms, from Fiyero:
To be sure, Sarima would be in her winter doldrums (as distinct from her spring moods, her summer ennui, and her congenital autumn condition). (3.11.1)
She seems alternately like a joke and a like cruel, politically-minded woman in these early descriptions. Of course, these depictions are coming from her estranged husband, who's currently falling in love with another woman, so they probably aren't entirely accurate. And it turns out his assessment misses a lot: Sarima is a decent mother, a smart woman, and actually quite likable. So let's see what makes her worth caring about.
Talk about your awkward family arrangements. This is the stuff afternoon talk shows are made of: a widow takes in her deceased husband's lover, who is partially to blame for his death, and their illegitimate son. They all live in an isolated castle with her catty sisters and her three crazy kids. One of the kids is killed by the lover, which at least prevents him from growing up into a serial killer. Wow.
Aside from adding some talk-show excitement and scandal to the book, what is Sarima really doing here? Well, she's definitely a lot more than Fiyero's wife. That might be her least important role in the book, so we'll go ahead and get it out of the way before turning to the thematic roles Sarima plays in the novel and her crucial relationship with Elphaba.
Fortunately for Elphaba, Sarima didn't have an Avril Lavigne reaction to Fiyero's secret girlfriend showing up on her doorstep. In fact, she never even fully acknowledges that Elphaba was Fiyero's lover.
See, Sarima is not only the Princess of the Arjiki Tribe, she's the Queen of Denial. This woman has her Scarlet O'Hara "I'll think about it tomorrow" routine down cold, and she goes through life refusing to see what she doesn't want to see, or hear what she doesn't want to hear.:
"Not unless I want to hear it, which is my prerogative. This is my house, and I choose to hear what I want." [...] Sarima did not like to be ambushed in her own home. Time enough to consider these sudden implications. When she felt up to it. And not until. (22.214.171.124-55)
Sarima's denial reveals a deep-seated fear within her; she's too afraid to face ugly truths or reality. She is painfully aware of the "thin pretense of authority that scarcely masked her fear of the present, the future, and even the past" (126.96.36.199).
This is really kind of ironic, because Sarima is a very strong and smart woman. She manages her crazy, catty sisters with some skill. She's a good mother, to Nor at least (you can read more about this relationship in Nor's character section). She can also go head to head with Elphaba, which few people can do.
Above all else, Sarima seems to get Elphaba in a way that few characters in the book do. In fact, we think Sarima may understand her better than anyone else in the book. She's oddly insightful when it comes to the green woman, and she often plays pop psychologist on her:
"You will indeed, even if you don't know it. You will have nothing left to tie you to the world. But I know my own limits, Auntie Guest, and I know what you're here for." (188.8.131.52)
Elphaba undergoes a huge number of shifts at Kiamo Ko – it's where she becomes a witch, reluctantly accepts that she is a mother, becomes part of a family (however dysfunctional), and is reborn after her stint in a nunnery, crippled with grief over Fiyero. In short, Elphaba learns to live again at Kiamo Ko, and Sarima plays a large role in all of that.
Sarima is tied to a huge number of the book's major themes: family, memory and the past, forgiveness, guilt, and friendship. She's this sort of out-of-left-field major character. We may have been expecting to hate her on Elphaba's behalf (she is the wife of Elphaba's lover after all), but we end up growing extremely attached to her.
So Sarima's ultimate fate is really awful. Because we ended up liking her so much, her death packs a huge punch. Sarima's character is part of the whole "appearances can be deceiving" theme running throughout Wicked. People we expect to be good aren't always, and vice versa. Sarima and her family's death is a really painful example of the Wizard's oppressive regime, and her loss is really almost more than Elphaba can bear.