Christos sang Violetta in Verdi's La traviata, one of her signature roles, at New York City Opera and Pittsburgh Opera, and appeared with the Lyric Opera of Chicago, San Diego Opera, Opera Theatre of St. Louis, and other companies. She graduated from Duquesne University with a bachelor's degree in music in 1969. Her graduate studies were at Carnegie Mellon University with voice teacher Lee Cass.

After moving to New York she debuted at the New York City Opera in Puccini's Turandot in October 1975. Her Pittsburgh Opera debut was in Puccini's La Boheme during the 1977-78 season; subsequent roles with the company included Donna Elvira in Mozart's Don Giovanni, Marguerite in Gounod's Faust and Micaela in Bizet's Carmen.

In 1984, she sang Micaela in a New York City Opera production broadcast on Live From Lincoln Center.

She also appeared in Bizet's The Pearl Fishers, Donizetti's The Elixir of Love, Glinka's Ruslan and Ludmilla, Mozart's The Marriage of Figaro, and Prokofiev's The Love for Three Oranges.

According to the Gazette, Christos had a distinctive dark vocal coloration that often led to comparisons with her idol Maria Callas.

A popular teacher, she had studios in New York and at her Connecticut home. She died from complications from multiple myeloma, a form of blood cancer she suffered from for six years, according to the Post-Gazette.