By Daniel Chertoff and Michael Tobin

When we tell people we co-authored a novel, the first question is usually, “What is it about?” The second, almost inevitably, is more interesting: “How do two people write a book together?”

It’s a fair question, and it carries a quiet assumption—that writing is, by nature, solitary. The image persists: a lone figure at a desk, wrestling with sentences in silence. At first glance, co-authoring seems like a contradiction. Yet it is far more common than most readers realize. From Good Omens by Neil Gaiman and Terry Pratchett to The Talisman by Stephen King and Peter Straub, from This Is How You Lose the Time War by Amal El-Mohtar and Max Gladstone to The Unhoneymooners by Christina Lauren (the pen name for the writing duo Christina Hobbs and Lauren Billings) to The Difference Engine by William Gibson and Bruce Sterling, collaboration has quietly shaped some of the most distinctive voices in modern fiction.

Still, knowing that others have done it doesn’t explain how it works.

There is no single method. Some co-authors divide the work by character or point of view. Others pass drafts back and forth, revising each other’s prose until the voices merge. Some outline extensively together, then write separately. Others sit side by side, literally talking the book into existence.

We discovered our method gradually, almost by accident. We had been collaborating in looser ways for years—weekly conversations about literature, long discussions about cybersecurity and narrative, and the exchange of drafts and feedback. The novel that became Resonance emerged not from a plan but from a shared fascination: Paris between the wars, the literary world orbiting Ernest Hemingway, and the magnetic pull of Shakespeare and Company.

At first, we worked in a simple back-and-forth rhythm. Michael would send a piece of writing; Danny would respond. But over time, something shifted. Instead of reacting to what had already been written, we began to talk before writing. We debated, shaped, dismantled, and rebuilt scenes in conversation. We would ask: What is this moment really about? What is missing? What does it lead to? Only after that would Michael sit down to write a draft, which we would then examine together.

It is, in retrospect, what might be called a “talk-write” process. But that description is too neat. What actually happens is messier, more alive. The writing becomes the visible trace of an invisible dialogue.

That dialogue is the heart of co-authoring and its greatest challenge.

The two of us are not similar in personality. Yet we are, if anything, what one of us once called “two older alpha, micromanaging types.” That combination could easily have led to endless conflict. There were moments—especially early on—when it nearly did. Each of us had strong opinions, strong instincts, and a deep investment in the work.

The question, then, was not whether conflict would arise. It was what to do about it.

What we discovered, slowly, was that disagreement can be productive when it is anchored in a shared commitment. In our case, that commitment was simple and absolute: the work had to be excellent. Not good enough. Not passable. Excellent. That standard became the arbiter of our disputes. It allowed us, imperfectly but persistently, to set aside ego in favor of the outcome.

This does not mean the ego disappears. It means it is subordinated to the greater good.

One of the most important shifts in our collaboration came when we learned to interpret each other’s reactions. Danny would sometimes say, “Something’s missing,” without being able to articulate exactly what. Early on, Danny’s inability to specify what was missing frustrated Michael. Over time, we came to see those moments not as obstacles but as signals—Danny’s discomfort, even when unclear, was data. Michael came to understand that it pointed to a gap in the text that needed exploration.

A particular chapter featuring Hemingway became a turning point. To Danny, the first draft felt incomplete, though he couldn’t fully explain why. Instead of dismissing that reaction, Michael treated it as a clue. The result was a deeper, richer revision—one neither of us could have produced alone.

This is one of the paradoxes of co-authoring: clarity often emerges from ambiguity. One person senses that something is amiss; the other works to uncover what it might be. The process can be inefficient, but it can also be transformative.

Trust is what makes the process possible.

Without trust, criticism feels like an attack. With trust, it becomes collaboration. Over time, we developed confidence that every comment, however blunt, was in service of the work. There was no hidden agenda, no scorekeeping. Just a shared effort to create something better than either of us could produce alone.

That trust also reshaped the experience of writing. Writing alone can be isolating—a mixture of “agony and ecstasy,” as Michael describes it. In this project, he was not alone. Even when he was physically at the keyboard, drafting sentences, the conversation continued internally. The work felt inhabited.

Yet this raises an uncomfortable question: Who, exactly, is the author?

In our case, Michael wrote most of the text. He was the one who turned conversation into prose. Danny contributed ideas, structure, literary history and theory, research, and critique. He also shaped what was written, even if he didn’t write it directly.

So is that a fifty-fifty collaboration?

Michael insists that it is—without hesitation, without qualification. Danny remains more ambivalent. Part of him looks at the pages and thinks, “Michael wrote this.” Yet another part knows the pages would not exist in their current form without our ongoing dialogue.

In the end, the question may be unanswerable—or perhaps it is simply the wrong question. Co-authoring resists mathematical division. It is not like splitting a bill or dividing a pie. It is closer to a conversation that produces something neither speaker could have said on their own.

There are practical benefits to this kind of collaboration. It mitigates the loneliness of writing. It creates accountability—your partner is always waiting for the next chapter or revision. It can even accelerate the process, as ideas are tested and refined in real time rather than in isolation.

But the deeper reward is less tangible. It lies in the emergence of a third voice—not Danny’s, not Michael’s, but one that arises between us. A synthesis. A resonance.

That word—resonance—became the title of our novel, but it also describes the process that produced it. Two distinct frequencies interact, amplify, sometimes clash, yet ultimately create a richer sound.

Looking back, what is most striking is not how difficult the process was but how well it worked. Given our personalities, the potential for conflict was enormous. Yet, as Danny put it, “It’s unbelievable how little strife there was because of our determination to work symbiotically to make something bigger than the sum of its parts.”

That determination—to place the work above all else—made the difference.

Writing Resonance was, in the end, a joy, not because it was easy but because it was shared. The process deepened our respect for each other and, perhaps more importantly, our understanding of what collaboration can be.

We are already at work, at least in imagination, on the next novel—more ambitious and more complex, set across different times and worlds. We now know the process will not be seamless. There will be disagreements, uncertainties, and moments of doubt.

But we also know something else: somewhere within that process, if we remain committed to excellence and to each other, a voice will emerge that belongs to neither of us alone.

And that is the real answer to the question. How do two people write a book together?

They don’t. Not exactly. They create the conditions under which something else can. Just like this essay.