'We are the Thirteen, from now until the darkness claims us'
Asterin was described as beautifully wild with golden hair, gold-flecked black eyes, heavy breasts, and a broken nose. While over a hundred years old, she appeared to only be in her mid-twenties. Additionally, she had sharp, retractable iron nails and teeth, common to Ironteeth witches. The word "UNCLEAN" was branded across her abdomen.
Wild and thrill-seeking, Asterin relished the wind in her face. Her temperament is often described as the fire to Manon's ice and balanced by Sorrel Blackbeak's stone. She grinned wickedly and roared while riding her wyvern, one of her few joys. Outspoken and opinionated, she was willing to stand up to her coven leader, Manon, regardless of any repercussions, but values Manon and her safety above all else. She is brash & fierce.
Asterin is introduced as Manon Blackbeak's second-in-command.
The Thirteen are training at the Ferian Gap with the rest of the Ironteeth witches. In reflecting on the tensions between the Ironteeth Clans in such close quarters, Manon recalls having to separate Asterin and a Yellowlegs witch when the two got into an altercation; afterward, Manon disciplined Asterin, breaking her nose in the process. Asterin wears her broken nose with pride now. Vesta Blackbeak and Asterin have been chatting with the other witches to gather information about Baba Yellowlegs's death but to no avail.
Asterin, along with the rest of the Thirteen, accompanies the group of Ironteeth witches to the wyvern training pits, where she vigilantly guards Manon.
As Manon and Iskra Yellowlegs trade barbs in the mess hall, Asterin laughs, then flippantly bows her head to the Yellowlegs heir as she passes. Later that day, the Thirteen head to the Gap to fly on wyverns for the first time. Asterin is clearly undaunted and eager to fly. When Iskra arrives with her coven, Asterin quietly calls her a bitch. After the Thirteen take flight, Manon swears that she spots tears welling in Asterin's eyes. Asterin asks what to do now, and Manon replies that they should test out the wyverns.
During a meeting with her granddaughter, Mother Blackbeak admonishes Manon to ensure that Asterin guards her closely, perhaps unaware that Manon has already stationed her Second outside the Matron's room.
Asterin chooses Narene, a sky-blue mare with strength in stealth, as her wyvern mount, to aid in Asterin's scouting duties. No one challenges Asterin for Narene out of fear of the Blackbeak Second. Petrah Blueblood approaches Manon, eliciting a soft snarl from Asterin. When Iskra shoves Manon into the pit during Titus's fight with Abraxos, Asterin screams and tackles Iskra; she is still holding her when Manon emerges from the pit. Mother Blackbeak orders Asterin to be punished for allowing Manon to "fall" into the pit and ignores her granddaughter's request to wield the whip herself, instead of delegating the task to Iskra. Through the ordeal, Asterin refuses to cry out.
Asterin sticks closely to Manon's side when her commander goes to see Abraxos in the warrens.
Manon orders Asterin to occupy the Thirteen for the day so she can train with Abraxos, whose wings are weak from lack of flight and injuries in the fighting pit. Since the Matron threatened to gut her should she let Manon out of her sight again, Asterin hesitates. Manon questions her allegiances - whether she swears fealty to Manon or is Mother Blackbeak's spy - Asterin insists that she serves Manon, who then fleetingly wonders if she truly deserves this sort of loyalty. Manon asserts that she will be Wing Leader, and Asterin smiles and says that they know. The Blackbeak heir instructs her to add tumbling to the Thirteen's training repertoire and, when she can handle Narene by herself, to take to the skies when the Yellowlegs are flying. Asterin assures her that she has already commanded the Shadows to tail the Yellowlegs in the dining hall.
Asterin is first seen telling Elide she has witch blood, alongside Manon, who says she will help her escape and welcomes Elide to the Blackbeak clan.
When Manon agrees with the Duke & starts trying to choose a clan to be implanted with Valg stones, Asterin questions Manon's choices & strongly argues against it. Manon demotes Asterin as a result. She is withThe Thirteen when their meeting is interrupted by a man with a Valg inside him, & he injures one of the Thirteen before Manon kills him while the human inside begs for death. When Asterin finds out that the Yellowlegs witches are chained to tables & being forced to give birth, she confronts Manon & demands that the witches are let free, & is then demoted. Asterin almost leaves with Vesta when Manon refuses to listen.
When the witches return to Morath, Asterin asks for a private meeting with Manon and tells her a secret from years ago. She fell in love with a mortal man and got pregnant. She carried the baby full-term, which is rare for witches. But the baby girl was stillborn. Manon’s grandmother was furious. Asterin was heartbroken, but she healed and came back stronger than ever. She begs Manon to disobey her grandmother and not let the witches be impregnated. Manon feels a thread tugging at her. She and Asterin take off for Rifthold, where they leave a message for Aelin, before heading back to Morath. It is revealed that Vesta and Sorrel helped save Asterin’s life after the Blackbeak Matron casts Asterin out of the Keep for having a stillborn witchling.
On the way back to Morath, Manon and Asterin feel the return of magic. Morath is in chaos because of this.
Asterin is with the host of Ironteeth witches who sack Rifthold at the beginning of the novel. After Manon's trial reaches completion, Asterin is sentenced to death.
Asterin arrives bloody and beaten to the morning of her execution. Manon’s grandmother is going to allow more beatings from the other clans before the execution. But Manon exercises the power of execution. Her grandmother is furious. She will kill Asterin to spare her the torture. Asterin could tell Manon’s secrets and be free. She remains silent. Asterin whispers where to bury her body. Manon proceeds to save Asterin, who escapes Morath with the rest of The Thirteen.
Asterin is reunited with Manon when The Thirteen come to Manon's aid during the Battle against Maeve's Armada.
In Kingdom of Ash Asterin is a loyal follower to Manon, helping her find the Crochans. When Manon tells the Ironteeth about what her grandmother plans to do with the Witch Kingdom, Asterin helps her by showing her brand and sharing her story. In the final battle for Orynth she and The Thirteen Yield and she takes Manon's grandmother with her.
When Asterin takes part in the Yeilding, she explodes into light instead of darkness like normal witches.
Asterin and Manon are cousins, both descending from the Blackbeak Matron's line. Fiercely devoted to Manon, Asterin serves as her Second for well over a hundred years, defending her against other witches and even the Blackbeak Matron herself. Following Manon's rescue of Dorian Havilliard during the plundering of Rifthold, Asterin chooses to sacrifice her own life rather than expose Manon's secrets to the covens. However, Manon's love for her and the Thirteen prompts her to fight the Blackbeak Matron so that Asterin and the others can escape.
While tracking Crochans to the west of the White Fangs, Asterin attempted to fly over a storm and subsequently fell off her broom, destroying her broom and gravely injuring herself. A passing hunter witnessed her fall from the stormy sky and, over the course of several months, nursed her back to health and fell in love with her. Following her summoning to Blackbeak Keep, Asterin soon realized she was pregnant and tried to return to the Hunter but was prohibited from doing so by the Blackbeak Matron. When she gave birth to a stillborn witchling, the Matron branded Asterin and brutally beat her to near death. Ashamed, Asterin could never bring herself to return to the Hunter, despite her promise to, in fear that he would not be able to understand what had happened during her absence. In the years to follow, she witnessed him age into an old man, watching the sky as if waiting for something. When he died, Asterin searched for his body but to no avail. Even after all these years, Asterin never stopped loving her hunter.