Born in 1805 on the Lewis & Clark expedition, Jean-Baptiste Charbonneau was the son of the expedition’s translators, Sacagawea and Toussaint Charbonneau. Across The Endless River evokes the formative years of this mixed-blood child of the frontier, entering the wild and mysterious world of his boyhood along the Missouri. Baptiste is raised both as William Clark’s ward in St. Louis and by his parents among the villages of the Mandan tribe on the far northern reaches of the river.

In 1823, eighteen-year-old Baptiste is invited to cross the Atlantic with the young Duke Paul of Württemberg, whom he meets on the frontier. During their travels throughout Europe, Paul introduces Baptiste to a world he never imagined. Increasingly, Baptiste senses the limitations of life as an outsider; only Paul’s older cousin, Princess Theresa, understands the richness of his heritage. Their affair is both passionate and tender, but Theresa’s clear-eyed notions of love, marriage, and the need to fashion one’s own future push Baptiste to consider what he truly needs.

In Paris, he meets Maura Hennesy, the beautiful and independent daughter of a French-Irish wine merchant. Baptiste describes his life on the fast-changing frontier to Maura, and she begins to imagine a different destiny with this enigmatic American. Baptiste ultimately faces a choice: whether to stay in Europe or to return to the wilds of North America. His decision will resonate strongly with those who today find themselves at the intersection of cultures, languages, and custom.

The Lewis & Clark expedition has almost the same perennial appeal for readers as the Civil War and Lincoln. Why do you think this is?
I think Lewis & Clark is the emblematic American story, a kind of national myth about the discovery of the western part of our continent that happens to be true. It starts with the remarkable fact of the Louisiana Purchase: Napoleon needed money, the Americans wanted land, and the deal was done in secret in 1803. In one fell swoop Thomas Jefferson doubled the land mass of the country. But nobody knew what was out there! The idea of sending a small band of adventurers to find out immediately captures the imagination. Among them was a young Shoshone woman called Sacagawea and her new-born baby. The baby was called Pompy in Shoshone, son of the French-Canadian scout, Toussaint Charbonneau, and of Sacagawea. He made the entire journey to the Pacific and back with the Corps of Discovery strapped to his mother’s back as a papoose. Later, when the young family returned to St. Louis, he was christened Jean-Baptiste Charbonneau. He is the book’s central character.

What was it about Jean-Baptiste Charbonneau that led you to write a novel based on his life?
He is a fascinating combination of improbable origins and extraordinary experiences. And the more I learned, the more I was drawn to this character. His circumstances alone are amazing: born to Sacagawea at the beginning of the Lewis & Clark saga; the adopted son of William Clark, who was the most respected and influential government official in the trans-Mississippi West; he lived for much of his boyhood among the Mandan tribe; then was the guest of a royal duke when he spent five years in Europe as a young man. He had had the benefit of a European-style education, was conversant in English, French, and Spanish, and also spoke a number of Indian languages

So here was someone of mixed race, with mixed cultural backgrounds, speaking multiple languages. Even today that’s an impressive list, but imagine what that kind of destiny would involve on the frontier of the 1820s. You see, when we talk about American history, we most often talk in terms of groups who played a significant role: “the French”, “the Indians”, “the settlers”, and so on. Without our saying so, we refer to groups who share the same race, language, and culture. Fair enough… to a point. But we often forget that in this kind of overlap of cultures with extensive contact and rapid change, there are always some individuals with deep roots in more than one of these separate worlds.

These are the people who can go back and forth, who can live on either side of the divide. As a “mixed blood”—his father was white, his mother was Indian—Baptiste was able to function on both sides of the barrier. But he also had to figure out his own “in-between” path rather than remain an outsider, and that is what this story is about.

Now I had lived in France as a boy, and had gone to French schools, so I had a sense of what it meant to be bilingual and to grow up with two different cultural models, though of course they were far more similar than the two worlds that made up Baptiste’s background. After writing narrative nonfiction with The Piano Shop on the Left Bank, I knew that the contours of the story were important, but I also knew that, in the absence of records and documents, I would have to imagine the life he had known, both on the frontier as a boy and when he spent five years in Europe as a young man. It involved a kind of two-way mirror image of two very different worlds: Duke Paul’s view of the frontier when it was just about to change forever, and Baptiste’s view of Europe at a time when rapid industrialization, commerce, and democracy were all gathering steam and changing the entire landscape.

What was the biggest challenge you faced in bringing this time alive for the reader?
I’d say it was the difficulty of “un-learning the past.” It’s the same problem faced by historians and writers of historical fiction. We know what happens next in history, but a contemporary didn’t. You have to let your imagination play, as any storyteller does, and think of what these places looked like to your characters.

For example, for Duke Paul, how did it feel to see a herd of buffalo that covered the entire landscape, hundreds of thousands of animals that wandered the plains? Or to see a flock of birds so large and thick that the sun was darkened for minutes? We forget that North America was, less than two hundred years ago, just this place, and I’ve tried to capture that experience. On the other hand, what did Baptiste feel when he saw Paris in 1824? What were the noise and crowds like to him, and the carved stone buildings of Paris: the Louvre, the Invalides, Notre-Dame? And think of how strange something as obvious to the French as planted, formal gardens and trimmed trees and hedges must have appeared to him. I describe this fantastic place through his eyes, and the things he notices aren’t always what we would guess.

The two women Baptiste becomes involved with in Europe are very different, and yet they face some of the same challenges in making their way in the world. Is this a theme that you decided to develop, or did it come from the story?
Most of the book tells the story of the five years Baptiste spent in Europe as a young man. It seems clear that he would have had some close relationships with women during this time, and the period had its own rules and constraints. It’s hard to exaggerate how important it was for women to be married in the early 19th century; otherwise, they ceased to exist socially. So the two women Baptiste becomes close to confront this barrier in their own ways. Princess Theresa, a rich and independent widow nearly twice his age, takes him as her lover and teaches him how the little bubble world of court life operates. She has no illusions about their making a future together, and in this her attitude is very French: love and its many pleasures are to be savored in the moment, but life’s responsibilities will always come knocking at the door to take you away from that.

Maura, the daughter of an Irish-French wine merchant who also smuggles arms, is more impetuous. Like all women of the time, she is systematically excluded from having a profession, so her interest in medicine has no hope of fulfillment. When she meets Baptiste she learns that there is a place where the conventional rules don’t apply in the same way as Europe. Combined with her love for Baptiste, the very idea of the frontier, hard and unforgiving as it was in many ways, must have seemed like a very attractive escape from choices that were limited. She begins to see another path, and one of the book’s main directions is the life Baptiste and Maura imagine together.

So there are two love stories. In the case of Theresa, it’s the story of Baptiste’s coming-of-age emotionally and physically. Later, with Maura, he acts on what he has learned and considers returning to the frontier as a path with unique advantages, not just as an escape from his life as a perpetual outsider in Europe.

Are there ways in which this story has relevance to the choices we make in our own lives today?
In Across The Endless River we see a young person of mixed race who, through the accident of his birth, has access to privilege and power. He comes from that New World and gets to know the Old World. His challenge is to learn what he can from all that he is exposed to, and then to fashion his own path forward. As William Clark says to him at one point, “Lie low, and watch those around you.”

If there’s a lesson in this story that we can draw upon today, I suppose this is it. Life at the edges of two cultures can be tough, but it can also be an enormously fertile and rich place to be. It involves that skill that has come to be thought of as essentially American: re-inventing yourself.

Today we live at a time of unprecedented change. I suspect that with increasing contacts among peoples, languages, and cultures, that capacity for adapting and borrowing from other ways of life, always evident when we look back at history, will come to be even more valued in the future. In this sense—racially, linguistically, and culturally—Baptiste is a forerunner of what America is still becoming.