Vasilisa is a young noblewoman with a rare ability to see and communicate with chyerti, the nature and household spirits of old Russian folklore. Condemned by her village as a witch following a tragic bear attack, she rejects the traditional female paths of marriage or the convent. Disguising herself as a boy named Vasilii, she travels to Moscow to forge an independent destiny. Her journey places her at the center of political turmoil and the cultural clash between ancient magic and orthodox religion.

Morozko is the immortal winter-king and frost-demon of Russian folklore. He represents the fading magic of the old world, feeling his existence wane as orthodox religion spreads. He provides Vasilisa with crucial supplies, practical training, and a protective sapphire talisman. As a death-god, he often acts with cold detachment, but his ongoing interactions with Vasilisa challenge his immortal nature.

Aleksandr is Vasilisa's older brother, known in Moscow as Brother Aleksandr Peresvet or Lightbringer. He left home ten years ago to become a revered warrior-monk and trusted advisor to the Grand Prince. He is deeply pious and honors his monastic vows, but his loyalties are severely tested when his rebellious sister arrives in disguise.

Olga is the Princess of Serpukhov and older sister to Vasilisa and Aleksandr. She has fully embraced the traditional, confined life of a highborn woman in medieval Russia. Pregnant with her third child, she wields social power within her domestic sphere but fears the scandal her sister's defiance might bring to her household.

Kasyan is a wealthy, red-haired boyar who claims to rule a domain called Bashnya Kostei. He presents himself as a loyal lord seeking the Grand Prince's aid against mysterious bandits. He integrates smoothly into Moscow's elite circles, displaying a strategic mind and keen interest in Vasilisa.

Konstantin is a charismatic, golden-haired Orthodox priest originating from Lesnaya Zemlya. He views the old pagan traditions as demonic and is determined to purge them. Driven by religious fanaticism and a conflicted obsession with Vasilisa, he spreads a narrative that she is an evil witch responsible for her family's tragedies.

Dmitrii is the ambitious Grand Prince of Moscow. He seeks to consolidate his political power and secure his borders against Tatar bandits taking advantage of regional instability. Charismatic and eager to prove his strength, he often relies on Aleksandr for counsel and quickly admires the disguised Vasilisa's bravery.

Marya is Olga's young daughter and Vasilisa's niece. Like her aunt, she possesses the rare sight that allows her to perceive household spirits and ghosts. This trait frightens her mother and makes the young girl unusually sensitive to the unseen world hidden within the city.

Solovey is Vasilisa's magnificent bay stallion. Far more intelligent than an ordinary horse, he understands human speech and acts as a fiercely loyal partner to Vasilisa, embodying the untamed spirit of the wilderness she draws strength from.

Pyotr is Vasilisa, Aleksandr, and Olga's deceased father. A boyar from Lesnaya Zemlya, his sudden death prompts Vasilisa's flight into the wilderness and casts a shadow of grief over his children in Moscow.

Anna is Vasilisa's stepmother. She was terrified of the old spirits and deeply devout. Her recent death during the bear attack adds to the tragedy surrounding Vasilisa's exile from her home village.

Chelubey is a ruthless commander operating under dual identities. He acts as an official ambassador representing the Tatar warlord General Mamai while simultaneously leading the vicious bandit raids that terrorize the Russian countryside.

Eudokhia is the Grand Princess of Moscow and Dmitrii's wife. She shares the confined, domestic life of highborn women in the city and frequently expresses anxiety over her lack of children.

Sergei is the revered head and founder of the Trinity Lavra monastery. He serves as a spiritual mentor to Aleksandr and provides vital refuge to villagers fleeing the mysterious bandit attacks.

Father Andrei is the hegumen of the Monastery of the Archangel. He provides counsel to Aleksandr regarding court politics, advising him on how to handle the impulsive Grand Prince and the impending threat of war.

Polunochnitsa is a midnight-demon with dark skin and pale hair. As a chyert, she appears sporadically to offer cryptic advice and guidance to Vasilisa during her dangerous travels through the winter wilderness.