Lady Thalia is a vitrina who has been living in a mirror for the past four thousand years. She is in possession of a necklace which brings out the gold flecks in her "lovely" eyes. She wonders if her hair is better up or down, and Serafina tells her that when her hair is up, it frames her face beautifully that way and shows off her "lovely" eyes. Serafina also stated that her completion glows from within like the moon, but this may have been flattery.
Like all vitrina, Lady Thalia is shown to be very vain and to have a short attention span for any topic that isn't her. When Serafina and Ling first meet her, she was haughty and silent, but Serafina flattered so much that she'd finally deigned to speak with them. As a human, Lady Thalia was in love with her own reflection, and when she died, her soul became trapped in the glass. She is self-involved, and believes that there is no one more charming, or lovelier, more graceful, or wittier, or more captivating in every possible way than her. She is also never lonely, as she has herself to talk to. She is afraid of Orfeo, and cares for her friend Alma. She was also in love with Orfeo before he went mad.
She owns ruby drop earrings, gold hoop earrings, a necklace, and quite possibly more jewelry. Jennifer Donnelly misspelled her name "Talia." She offers advice on clothing, makeup, and jewelry to Serafina and Ling. She knows about all the talismans.