What do Greta and Jason have in common in the novel, The Unsinkable Greta James?

Greta and Jason were neighbors during their childhood, and they were both raised in Ohio. Later they both moved to New York City, where they saw each other on and off, maintaining an undefined yet consistently casual sexual relationship. Greta and Jason also shared a mutual disinterest in living an ordinary and conventional lives, and they both cared about their work and their art more than notions of stability or promises of family.