Early in my publishing career, I worked with a vaunted science fiction writer, one of the true masters of the field. His books consistently sold well, but then he published a book that sold in an outsized way. He’d always written novels that stood alone, so the repeated requests from readers and his publisher to provide a sequel surprised him and, to be honest, threw him off his game. Unaccustomed to doing this sort of thing, he wrote a pallid costume drama of a follow-up, and then another. Readers ultimately lost interest.

I thought about that scenario a great deal after readers began asking for a follow-up to my novel Blue. I’d envisioned Blue as an entity unto itself, something that ended with many of the story’s mysteries still intact. On top of this, I’d poured more emotion into this work over the six years it took me to complete it than I’d committed to anything I’d ever written. Costume drama was not an option. I wasn’t averse to writing a sequel, but I needed to have a story about which I felt at least as passionate – and I simply hadn’t found that story yet.

Then it dawned on me to look behind rather than ahead. There was a story I’d wanted to tell in Blue that I didn’t think fit for narrative reasons. Blue is in some ways about what happens when two worlds converge. However, there was a critical moment in the past – a Moment When Everything Changed – when the worlds first separated. I could only hint at this in Blue because doing anything more than that would have taken the novel on a long tangent.

I can write about this, I thought. In fact, I need to write about this.

That’s how Until Again came to life. Once I started it, the love I felt for the characters and the pleasure I felt in creating in these worlds came back to me. I wasn’t doing this because it was a good marketing idea. I was doing it because I’d found another story that mattered to me. The finished work is brief – only 88 pages, because it is about a moment, not a huge series of events – but I believe it is a complete story.

Over the years, I’ve had occasion to suggest countless times that writers revisit the worlds they created. It wasn’t until I wrote Until Again, though, that I fully understood why that return visit is so often like trying to reconnect with an old high school friend after you’ve moved in entirely different directions. It isn’t a matter of asking, “What else can I do with this?” It’s about asking, “Is there anything else in here that matters?” If a writer can answer the second question affirmatively, then it might be worth pursuing.