So, you’re on book three in your twelve-book series, Pasteboard Castles, which follows the lives of twelve friends after high school graduation. You’ve got Sibyl, the pint-sized scatterbrain, who marries a smooth-talking salesman with a closet overflowing with skeletons. Then there’s Rona, who draws boys like a porch lamp draws moths. If only she could get her BFF, Rikki, to take notice of her. Then there’s Felicie, who dreams of being a poet, while her parents insist she get a degree in something practical, like medicine or the law. Etc. Etc.
While each book in your series focuses on the life of one particular character, each book also features guest appearances from one or more of the other characters in the series. For example, Felicie may open her door to Sibyl, after Sibyl discovers one of her husband’s many indiscretions. Or a miserable Rona may go to Felicie for advice, after she learns that Rikki has started dating the man of her dreams.
Such crossovers are a great way to further build your characters, but they can also be confusing to readers, particularly if you don’t take the time (re)introduce them. Don’t assume that your readers have read ALL or even ANY of the other books in your series, even if you are on book twelve. Treat each book as if it were the ONLY one your readers will ever read in your series. If you pick up the strand of a plot line from one of the other books in your series, take the time to briefly outline it. Since Rona and Rikki began living together, etc… Since Sibyl left her husband, etc…by