If you believe mystery writers, an awful lot of murders take place in isolated country cottages or on ships at sea or on snowed-in trains. This kind of isolation makes it harder for the killer to escape, but it limits the cast, which makes the writer’s job easier. It limits the number of suspects, and readers know everyone from the beginning. Some more of them may turn up dead before the end, and one or two may turn out to be long-lost heirs or imposters. But the dramatis personae is stable from the beginning.
What do you do if your cast is less well behaved, though, given to popping in and out of the narrative in unpredictable ways? Maybe your plot structure leaves you no choice but to introduce a character early on and then sideline them or bring in a new character late in the game. Your readers naturally expect that your cast of characters is stable – that they know who the important players are as they read through the story. If you drop a memorable character halfway through, readers are going to subconsciously expect him or her to show up again before the end. If you introduce a new key character near the end, readers are going to feel cheated. Part of the joy of reading is anticipating what’s coming next, and readers get upset when you hand them something they couldn’t have seen coming.
I’m currently editing a story that, near the beginning, introduces a sharply-drawn character – the main character’s boss – who has an intriguing relationship with her. The boss later plays a key role in the main character’s life. The problem is, as the writer got deeper into the story, it grew to the point that it needed to be broken into three books, and the memorable boss we met at the beginning of book one doesn’t reappear until book two.
My client can’t just cut the character. She’s going to need him eventually, and readers need to know how the boss gets along with the main character before she undergoes some serious changes in that first book. The most straightforward solution would be to create some independent subplot involving the boss that my client could cut to from time to time as the story progresses, just to remind readers he’s still there.