Cassie was the name of Benny Russell's fiancée in New York City in the 1950s and was part of a fantasy reality that recurred to Deep Space 9 Captain Benjamin Sisko, probably due to the interference of the Bajoran wormhole aliens (known to Bajorans as the Prophets).
She worked at a diner and considered the opportunity to buy the business from its owner, Mrs. Jackson, to be a solid investment, one that would allow her and Benny to settle down and start a family. Benny, however, was reluctant to give up his dreams of being a writer and was further motivated when Incredible Tales agreed to publish his latest story at a higher than usual pay-rate. His exuberance was short-lived, the magazine ultimately rejected his story because of its focus on a black captain.
Cassie took the opportunity to once again try to convince Benny to give up his dreams and go into business. He refused.