When Alina's Sun Summoner powers first manifest, it pulls her out of the world she knows in the First Army and sends her to the Little Palace. Though the Netflix series heavily condenses Alina's arrival and experiences compared to the books its based on, several of the people she meets become important at various points. There's her fellow Etherealki, Marie and Nadia, and Genya the tailor. There are also those who train her, like the combat teacher Botkin Yul-Erdene and, of course, Grisha master Baghra (Zoë Wanamaker, aka Madam Hooch from Harry Potter). But who is Baghra in Shadow and Bone, really? Her history goes back far longer than anyone at the school suspects.
Warning: Spoilers for Shadow and Bone Season 1 (and a few from the novels) follow. Baghra is introduced in both series and novels as the old crone who trains Alina. Though the series doesn't make it clear, Baghra has a specific type of Grisha ability; she's known as a human amplifier. (Aleksander Kirigan is also a powerful amplifier which is why he can draw Alina's hidden abilities out, even though she's suppressed them.)
Baghra is one of the most powerful human amplifiers living, and, in the books, Alina needs her. Unlike the series, which posits Alina is only accessing a small fraction of her strength, the Alina of the books literally cannot do anything without a human amplifier to make the connection.
But Baghra's amplifier gift is also a red flag, which neither Alina nor the reader realizes until it is almost too late. Baghra's gift is one she passed to her son: Aleksander. Their powerful amplifier ability is one of the signs Baghra is secretly General Kirigan's his mother. It's also why, in the books, Alina believes Baghra when she says her son is not "Kirigan" at all, but The Black Heretic.
But what neither book nor show makes clear is that Baghra's abilities, which she passed onto her son, are a direct inheritance from someone else from history. She is the daughter of Ilya Morozova, the most powerful Grisha ever to live, and the man who created amplifiers in the first place. (It's why she knows the Stag is real, and what its antlers can do. After all, her father made it.) Moreover, Baghra and Aleksander share the same ability. Like her son, Baghra is a Shadow Summoner.
The difference between mother and son is Baghra learned the hard way not to use her powers for evil. The books explain this more clearly: As children, Baghra's younger sister had no abilities or (in Grisha terms) was born an "otkazat'sya." Baghra was jealous because their mother (who was also otkazat'sya) seemed to favor her younger child, while Baghra's fearsome ability to control darkness made her an outcast. In response, Baghra lashed out, accidentally killing her sister.
The good news for viewers is that Baghra survives the first book and the first season. And that's a good thing: At the end of Season 1, the Darkling survived his encounter with the Fold and is coming for Alina. She's going to need all the help she can get.
Shadow and Bone Season 1 is on Netflix now.