@Willow There was a period in which i was feeling out my gender. I wasn't sure whether i was man, woman, both, neither, somewhere in between. I had heard that Starbucks was a good place for maybe-trans people to try out names. So i went. I had decided on "Cassady", after Neal Cassady the beat poet. Gods, i was so pretentious back then. But it was reasonably nongendered, slightly moreso than the shortened version of my birth band.
After a few visits, someone misheard and wrote "Cassie". That felt nice. That was a woman's name. That someone could ever look at me and feasibly think "woman"-- that was unthinkable to me back then. I started shortening it to Cass. But over time, "Cass, short for Cassady" morphed into "Cass, short for Cassandra" without me even noticing.
My wife calls me Cass sometimes. (Mostly when they're annoyed with me, hah.) Cassandra is beautiful but also kind of a mouthful. So most everyone knows me as cassie.
My wife picked Willow for my middle name. I liked it.