Years after she started writing her debut novel, Chelsea Banning settled into Pretty Good Books in Ashtabula, Ohio, on a Saturday in early December for her first author signing.

She waited with neatly stacked paperback copies of her book, “Of Crowns and Legends”—which she calls a King Arthur reimagining that takes place 20 years after his death. She had props, including a crown, a little statue of a knight kneeling and holding a pen, and pictures of friends dressed as her characters, in medieval garb.