On November 8, 2019, Arizona Opera presented composer Gregory Spears and librettist Greg Pierce’s 2016 opera “Fellow Travelers.” Premiered at Cincinnati Opera, Lyric Opera of Chicago presented the work in March 2018, and Minnesota Opera staged it three months later. That is not a surprise to anyone who has heard its enchantingly original music. Yes, it has its Puccini-style moments, but it also relates to much earlier music and contains tonal vocal harmony rarely heard in 21st century opera. Spears’ music shows human grace and warmth one moment and counteracts it with chilling dissonance the next. Thus, he magnifies and intensifies the conflict between characters.