Anna Maria is a fiercely ambitious orphan growing up at the Ospedale della Pietà in 18th-century Venice. She experiences synesthesia, an automatic neurological condition causing her to perceive music as vivid explosions of color. This unique ability fuels her extraordinary talent on the violin. Driven by a desire for greatness and the honorific title of maestro, she dedicates her entire life to her art, often isolating herself from her peers.

Vivaldi is a young violin virtuoso and composer who serves as an instructor at the Pietà. He holds a reputation for musical genius as well as an arrogant, demanding personality. Recognizing a rare talent in Anna Maria, he takes her on as a private student and pushes her to prioritize music above all else. He is highly driven and expects total dedication from the orchestra members.

Paulina is a quiet orphan at the Pietà, nicknamed "Little Paulina Rabbit" for her small stature and delicate frame. She plays the oboe and values personal connections highly. Unlike those who prioritize ambition above all else, she believes in the importance of loyalty and emotional support among the girls.

Agata is a calm, kind-tempered girl who plays the pianoforte. She forms a tight-knit trio with Paulina and Anna Maria, providing the emotional comfort the girls lack from traditional families. She faces recurring health issues but maintains a strong sense of hope regarding her future and her mother.

Chiara is a confident, polished violinist who earns a spot in the Pietà's professional orchestra, the figlie di coro, at a young age. Despite being viewed as competition by ambitious junior musicians, she is empathetic and values camaraderie. She attempts to bridge the gaps between the highly competitive players.

Elisabetta is a wealthy Venetian woman and a crucial financial patron of the Pietà. Her large contributions to the institution command deference from both the staff and the students. She uses her resources and significant societal influence to assist women navigating the strictures of 18th-century Venetian society.

Sister Clara is a nun at the Pietà tasked with caring for the orphans and overseeing their general education. She is less physically imposing than some of the other sisters and possesses a somewhat kinder demeanor. She assists in enforcing the strict schedules that govern the girls' daily lives.

Sister Madalena is a large, strict nun who enforces rigorous discipline at the Pietà. She maintains order among the girls, hands out harsh punishments for infractions, and carefully monitors the older students to determine their suitability for marriage or manual labor.

Tartini is one of the greatest composers of the era and a personal favorite of Anna Maria. He represents the pinnacle of musical achievement in Venice and commands deep respect from the young musicians.

A young woman working in 18th-century Venice who conceives a child she cannot afford to raise. Facing severe poverty, she leaves her baby at the Pietà with a small note and half a playing card, hoping her daughter will find a life filled with opportunity.

Sanza is a violinist in the Pietà's professional orchestra. She serves as one of the primary competitors for the coveted first-violinist position within the ensemble.

Prudenza is a violinist in the elite figlie di coro. She faces the harsh realities of the Pietà's music program when she falls out of favor with the instructors.

Bianca is a member of the figlie di coro who works on specialized musical projects. When fatigue impacts her performance, she faces sudden removal from the orchestra.

Sara is a young girl at the Pietà who sleeps near Anna Maria in the dormitory. She often cries herself to sleep as she adjusts to the difficult realities of orphanage life.

Signor Conti is one of the music instructors at the Pietà. He fills in during absences but is considered by ambitious students to be a less effective teacher than the primary maestros.

Anastasia is a musician in the figlie di coro who collaborates on specialized musical projects for the Pietà.

Lorenzo is an important, wealthy donor to the Pietà. The staff frequently organize musical performances specifically to secure his continued financial support and goodwill.

Anna is a young musician who joins the Pietà. She quickly catches the eye of the music instructors and is selected for special mentorship, walking a path similar to older prodigies.

Gertrude is an older woman living in the less glamorous sections of Venice. She keeps track of the belongings and histories of the women in her community.