Alexandria is a seventeen-year-old half-blood who has spent the last three years living on the run with her mother. As a half-blood descendant of Greek demigods, she possesses enhanced strength and speed but lacks elemental magic. She returns to the Covenant after a tragedy, facing the threat of forced servitude if she cannot catch up with her peers in Sentinel training. She is fiercely independent, highly loyal, and prone to reckless acts of defiance against the rigid Hematoi social hierarchy.

Rachelle is a pure-blood Hematoi and Alex's mother. Despite her elite lineage, she possesses only weak control over the air element, making her an outlier in a society that prizes elemental strength. Driven by a desire to protect her daughter, she made the controversial choice to flee the Covenant and live among mortals. She harbors deep secrets about her past and the true nature of her family.

Aiden is a twenty-year-old pure-blood Sentinel who dedicates his life to hunting daimons, a path unusual for the privileged pure-blood elite. He assumes responsibility for Alex's summer training at the Covenant, pushing her physically and mentally so she can avoid a life of servitude. Burdened by the traumatic loss of his parents, he serves as the primary guardian for his younger brother. He projects a strict, disciplined exterior that conceals his protective instincts.

Caleb is a half-blood trainee at the Covenant and Alex's steadfast best friend. Unlike Alex's impulsive and rebellious nature, Caleb provides a grounding, pragmatic presence, often advising her to exercise caution. He understands the unfairness of the Hematoi social hierarchy but generally chooses to operate within its boundaries to survive. He offers crucial emotional support as Alex readjusts to her old life.

Lucian is a powerful Minister on the Hematoi Council, Alex's pure-blood stepfather, and Rachelle's husband. He exudes wealth, authority, and arrogance, firmly believing in the superiority of the pure-blood elite. He wields immense political influence and takes a sudden, suspicious interest in Alex's return to the Covenant. He operates with calculated precision, viewing the people around him as strategic assets.

Seth is the Apollyon, an exceptionally rare and powerful half-blood capable of wielding all four elements as well as akasha. Covered in shifting, mystical tattoos, he holds a unique but politically constrained position within Hematoi society. He is arrogant and painfully blunt in his social interactions, but he shares an intense, inexplicable connection with Alex that frequently draws him to her side.

Marcus is the Dean of the North Carolina Covenant and Alex's uncle. A former Sentinel himself, he represents the strict authority of Hematoi society and enforces its rigid rules. He initially displays hostility toward his niece, proposing she be sent into servitude rather than reinstated as a student. He demands excellence and discipline, serving as a harsh evaluator of Alex's progress.

Matt is a human high school student who dates Alex during her time living in the mortal world. He is completely unaware of the existence of gods, Hematoi, and daimons. He grows frustrated with Alex's secrecy and becomes horrified when he witnesses her unnatural strength during a physical altercation.

Kain is a half-blood Sentinel whom Alex knew from her childhood years at the Covenant. He assists in patrolling pure-blood parties and serves as an elite warrior against daimon threats. He represents the ideal path for a talented half-blood willing to serve the Hematoi Council.

Leon is a pure-blood Sentinel and a close friend to Aiden. Unlike many pure-bloods who look down on half-bloods, he recognizes Alex's potential as a fighter. He advocates for her reinstatement at the Covenant when Dean Marcus attempts to send her into servitude.

Lea is a half-blood trainee at the Covenant and a long-standing rival to Alex. She actively antagonizes Alex, using cruel gossip and rumors to provoke physical altercations. She closely monitors Covenant politics and social dynamics, frequently trying to align herself with those in power.

Grandma Piperi serves as the oracle for the Hematoi, acting as a conduit for the gods' foresight. She lives in isolation deep within the marshes near the Covenant. She delivers chilling, cryptic prophecies about the students' futures, shaping the fears and decisions of those who hear her warnings.

Deacon is a pure-blood student and Aiden's younger brother. Still reeling from the tragic murder of his parents, he copes with his grief by sneaking out to parties and consuming excessive alcohol. Despite his struggles, he is friendly, welcoming, and quick to befriend Alex upon her return.

Jackson is a half-blood student at the Covenant and Lea's ex-boyfriend. He shows persistent romantic interest in Alex, frequently seeking her out at social gatherings and hosting parties. His advances often cause friction with Lea.

Olivia is a half-blood student training at the Covenant. She is a friendly presence in Alex and Caleb's social circle. Her mutual affection for Caleb highlights the strict societal limits placed on half-bloods, who are denied the right to marry or build traditional families.