Fact and fiction sat across from each other over coffee one morning this week. They also happened to be brother and sister.

“I write history and was jealous of the freedom that you had,” Paul Schneider said to his sister, Bethany (Bee) Ridgway.

“With fiction, you can do whatever you want,” she agreed. “As an academic, I’m so pencil-licky about things. I just busted free. It was the greatest thing I’ve ever done.”

Mr. Schneider is a critically acclaimed nonfiction writer and editor, and Ms. Ridgway is a professor of English literature at Bryn Mawr College. On Wednesday night this week, both read from their respective new books at the Bunch of Grapes Bookstore in Vineyard Haven.

Mr. Schneider’s upcoming book, his fifth, is Old Man River: The Mississippi River in North American History, a historical, natural and cultural look at the famed river. Henry Holt and Co. is the publisher.

Ms. Ridgway’s novel, The River of No Return, her first, is a time-traveling story that is a “mashup” of London in the Regency era, James Bond spy adventure and corporate mystery. Penguin is the publisher.

Coming from a large family of writers (two older sisters are published authors, their mother is a writer and their father a minister-turned poet), Ms. Ridgway was the last one to write a book.

Seated in a small coffee garden in downtown Edgartown, Mr. Schneider and Ms. Ridgway recalled growing up with a father as minister, always on deadline for his sermons.

“Every week he had to have a sermon written. It was a big drama whether it was going to get done. So we saw the writing process all the time,” Ms. Ridgway recalled.

“That’s interesting, I never thought of it that way,” Mr. Schneider said.

Ms. Ridgway wrote her book without telling anyone in her family — except her brother.

“They were all writers and I didn’t want them to know I was doing this crazy thing,” she said. “He was the only one who knew, which tells you something about our relationship.”

The novel began seven years ago.

“I was living in this house in Vermont which had been built in 1790 and renovated in 1970, so if you looked out the windows it was this old wrinkly glass . . . and if you turned around and looked inside it was like a psychedelic ski shack,” she said. “I think living in that house I got all time traveled out.”

“In my mind I thought — what would it be like if instead of a house it was a person who had this totally double experience.”

She sent a character sketch to Mr. Schneider. She forgot about it, and later returned to it as a novel form.

Mr. Schneider’s book began as a father-and-son trip down the Mississippi River with his son Nathaniel.

“It was tough going at first because, pardon the puns, but the Mississippi is deep and muddy and wide, and it was hard to figure out how to get a hold of it,” he said.

“It ended up being really fun and I’m happy with it. It’s similar to The Enduring Shore, [his early, popular book about Cape Cod, the Vineyard and Nantucket], my oeuvre,” he laughed.

“He has an oeuvre,” Ms. Ridgway whispered. “It’s kind of gross,” she added with a sisterly expression.

“And then Bethany had to put a river in her book, too,” Mr. Schneider returned.

Rivers have played a significant role in their lives. Growing up in Amherst, as children they often played along the Connecticut River.

“He did really crazy things on that river, sometimes I did really crazy things on that river,” Ms. Ridgway said. “Like taking a canoe out on the flood waters.”

“Really all manner of weird boats,” Mr. Schneider added.

Or jumping off a bridge that goes to Northampton.

“That was exciting,” Ms. Ridgway said.

“Yeah that was crazy, it could have been tragic,” Mr. Schneider said.

“But instead it was really awesome,” said Ms. Ridgway. “I was a little girl and he and his friend Warren took me out on the river in the canoe. They beached it on one of the pylons and they went and jumped off the bridge, and they left me in the boat. Which I thought was perfectly great and fun, so did they.”

It wasn’t until years later that Ms. Ridgway casually told their mother.

“She had a retroactive heart attack,” Ms. Ridgway said. “She still hasn’t forgiven me. We’re both totally at fault.”

Coffee over, they lingered, discussing possible formats for the book reading. Perhaps they would introduce each other, pretend to be each other or just do a song and dance and leave before anyone noticed.

Now that Ms. Ridgway has officially joined the family bandwagon of writers, it begged the question: Would they ever write a book together?

“Oh,” Mr. Schneider paused to consider.

“I think we could,” Ms. Ridgway said. “I actually think we could do it.”

“That’s a good idea,” said Mr. Schneider.