Princess Rosamond Cantacuzino was an old woman who lived in Smyrna in Lyra's world. Vaclav Kubiček gave Lyra Silvertongue her name in the clavicula and Lyra subsequently visited her grand house along the waterfront.
Princess Cantacuzino's dæmon, Phanourios, became besotted with a nightclub dancer her brother unrepentantly declared his mistress when she was around nineteen or twenty. His obsession for her forced the Princess to feel the same passion.
An object of ridicule, she was unable to accept any marriage offers. She pleaded with her dæmon and eventually was forced to live with the dancer, pretending to be in love. They shared a bed and the Princess joined her partner's occupation, despite considering it wretched. Together they attracted a bigger audience and achieved great success and wealth. However, her dæmon wished to become the dancer's and when the lazy, vain, incurious marmoset dæmon became a slave to the poppy, Phanourios had his obsession returned.
Princess Cantacuzino knew it was time to leave and, ready to die, she tore herself away from them one night in Beirut, leaving him with her after all three endured the pain and terror of separation. She returned to her family but was unable to marry given her solitary state.
She had no husband or children and her friends and associates were embarrassed by her state and avoided certain subjects when talking to her. Their pity and attitude caused her great boredom and despair that was only lessened when Mr Kubiček allowed her to meet others in similar situations.
She had met Lord Asriel, around thirty years before meeting Lyra, at a reception in the Egyptian Embassy in Berlin. She asked Lyra to watch out for her dæmon at the Blue Hotel and promised to keep her visit secret from her great-nephew Olivier Bonneville. She described the boy as stubborn and his father, Gerard Bonneville, as a 'ne'er-do-well'.
The Princess was very old and dressed all in black. Her eyes were small but bright among the wrinkles and lines of her face. Her voice dry, astringent and amused, and she struck Lyra as simultaneously appearing both fierce and vulnerable
Princess Cantacuzino's dæmon was Phanourios, a particularly beautiful black cat. His passion for the dancer led to their eventual separation. The Princess speculated that he may have ended up at the Blue Hotel.