I have been struggling with flashbacks in my novel - how to lead into them, when to introduce them, and how to determine whether they are necessary. Done incorrectly, they can jump you out of the narrative and   yet sometimes they are imperative to providing backstory and helping readers to understand a character's motives. Flashbacks are old news, perhaps essential news, but they lack immediacy because they are not  being told in story time. 

A quick search of tips on how to write flashbacks generated the following guidelines:

1) Ensure the transition to the flashback is clear. Often writers use a grammatical shift to signal their start i.e. if you are writing in the present shift to the past tense, if you are writing in the past  tense shift to the past perfect and then simple past and then back to  past perfect.

2) Keep them short.

3) Have a link to something in the previous scene i.e. a trigger or catalyst in the character's experience that leads them to think about  the past.

4) Use them sparingly.

5) Have them follow a particularly strong scene.

This is all well and good, but how are they best presented - as a  scene with dialogue, or as expository?  When? In the first chapter, second, fifth? And how long is too long - a page, two pages, five?

As before I decided to consult some of the books on my shelf to see how they handled flashbacks. In this case, since I am writing a novel about a moderately dystopic future, I pulled four novels that are of a similar nature - The Road (Cormac McCarthy), Oryx and Crake (Margaret Atwood), The Year of the Flood (Margaret Atwood) and World Made By Hand (James Howard Kunstler). The results:

The Year of the Flood - Atwood writes in the present tense for one of her main characters Toby and then shifts to the past when doing a flashback. The first flashback occurs in chapter 5 and consists of the  entire chapter (4 pages). It is presented as a description of an event in real time, rather than an expository of the character remembering the event. The event is the character going to seek a gun, the trigger or catalyst in the previous chapter is the use of that gun. Chapter 6 is also a flashback with more expository summary of events. The trigger is also the gun.

The Road - McCarthy writes in past tense. There is one minor flashback on page 13 - a main character remembering a day fishing with his uncle. It is also presented in past tense, but the author writes that he used to go fishing with his uncle. The flashback is a scene  without dialogue. The trigger is the character thinking "You forget  what you want to remember, and you remember what you want to forget." It is a page long.  There is a flashback of more substance on page 55.  It is presented as a scene with dialogue and is three pages long. We know that it is a flashback because the child's mother is present in it and not in the preceeding parts of the novel.

Oryx and Crake - Atwood follows a similar convention as the one she utilized in The Year of the Flood. The story is written in  present tense and flashbacks in past tense. The flashbacks are chapters unto themselves in alternating groups of two to seven i.e. two chapters  in present time, three flashback chapters and so on.  In this manner the story alternates between the character's present and past.  Atwood uses the technique of changing the character's name from his present  name to his past name to help the reader easily differentiate between  the time periods. The chapters that outline the past contain more summary expository than the chapters in the present but also in the form of scenes.

World Made By Hand - Rather than using flashbacks, Kunstler has included short expository backstory paragraphs that explain how the character got to where he is. These first start appearing in chapter three and there are not many of them so the story is not too disrupted. Since it is told from the first person POV, the effect is almost like the main character turning to address the reader.

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