Informing the Reader without Expo-dumping
...or how much expo-dumping can you do without completely pulling your reader out of the plot.
The book I'm writing deals with a brother and sister (16 and 13) who spend the latter part of their summer with their Grandfather, as their parents will be out of the country, due to respective work issues. The issue I'm dealing with, is trying to sufficiently explain the why of the kid's being sent to the Grandfather's, without pulling an 'as you know, Bob.' The parents being gone is admittedly the excuse to have them stay with the Grandfather for an extended period, but the locations of each parent contain plot hooks for (hopefully) further adventures. So I feel it needs at least some establishing.
As written so far, the brief prologue gives a vague hint of the supernatural adventures to come when they get their Grandfather's, without directly dealing with any of the protagonists. It's brief, and gives an idea where the story will go.
The current Chapter One details 'The Incident,' which is what ensures that they're sent to the Grandfather for far more time than the brother would have wished. The brother had hoped to convince the parents that the two of them could be trusted to spend at least part of the summer at home by themselves, with the neighbors nearby for emergency purposes. His primary motivation was not wanting to spend the majority of the summer away from his friends, the secondary one was that he wanted to apply with said friends for a coveted summer job at the local movie theater. Missing a couple weeks at the end of the summer might work; missing half the summer wouldn't endear him to anyone hiring. He had been making a habit of getting home from school before/at the same time as the sister 'to make sure nothing happened', and generally being a rather overbearing older brother in an effort at 'responsibility.' Things finally come to a head the day his friends convince him to run by the theater to pick up applications, whereupon he leaves a 'Don't be an Idiot' message on the answering machine for his sister, which the sister takes badly. Cue the very kind of shenanigans the brother had hoped to avoid and cut to the two of them heading off to the Grandfather's for the month of July on. Chapter Two picks up with the arrival at the Grandfather's and off we go.
My question is, how much detail of the backstory and intentions can I reasonably have the brother tell his friends, and by extension the reader, without it becoming an exposition dump? I'm writing in third person with POV shifts, but I don't want to spend too much time in the characters' heads, since it detracts from the action, which is really the focus of that chapter.
Would it be better to begin with the Grandfather, preparing for their visit or speaking to someone about their visit and the why and then go into 'The Incident' in Chapter Two? Or go through 'The Incident' with minimal explanation of why the brother wants to get home so badly, and then have the Grandfather provide the backstory in Chapter Two? Or just get them there, have them meet the other characters, and piecemeal it out?
I'm trying to keep the tone on the level of an adventure, with both lighter and darker moments, and after the slightly
ominous prologue, the relatively comic nature of 'The Incident' seems like the best place to go to keep things balanced, at least until the adventure gets into full swing. And when it does, I'm not sure when the best moment to mention 'My parents are gone because of x.' is.
Assuming the Incident you refer to is your inciting incident, one common technique is to essentially conceal this incident from the reader and begin the story with the reaction to the incident. In this case, that would be their arrival at the grandfather's home. You can establish the animosity between the brother and sister in the opening pages, to establish their relationship, but concealing the cause of their journey would let you create a sense of mystery which would draw the reader into the story. In other words, let the reader wonder what's going on.
As an experiment, I suggest you try cutting everything before their arrival at the grandfather's, just to see the effect. Readers like to connect with the main character right away, so begin the book from the main character's perspective. Later on, when it becomes relevant, you can reveal the nature of the Incident and the parents' trips.
Some well known books that use this technique are Harry Potter and the Philosopher's Stone
(the inciting incident being the murder of Harry's parents), and The Hunger Games
(in which the inciting incident is the death of Katniss's father).
This is a particularly useful approach when the inciting incident happens a long time before the main character enters the story, but it can work well in other cases too.
Of course, the opposite approach can also work. You could begin the book on the day the Incident occurs. I would still open with the main character's perspective. Show him perhaps trying to get the theatre job. Then have the incident disrupt his plans.
One book that uses this technique is Awakening
by Kelly Armstrong. The story starts with an important but normal challenge in the main character's life -- the first day of a new year in high school -- which is then disrupted by a supernatural event that gets her sent away and changes her life forever. Another example is City of Bones
in which the main character's fun excursion to a night club changes her life forever (she witnesses a demon being killed, but only she sees it and the demon killers).
Either way, I would be inclined to avoid a prologue if possible. Instead, perhaps you could find a way to give a little hint (perhaps even on the first page) that the story will involve something extraordinary, so the reader has a sense of what's in store, but will be held in suspense for a little while.
A couple of other tips...
* Keep in mind the general rule that exposition should occur on a "just in time" basis. Little bits of information inserted at the moment they are relevant is better than an infodump, especially in an action-driven story.
* Try not to shift points of view if you can avoid it. If you must, do so mostly at chapter breaks. Readers want a character they can get attached to, and too many POV shifts, especially early on, can weaken this connection. It sounds like the brother is your main character, so I would stick with him as much as possible, if not exclusively.