On writing a trilogy.

Advice for writers typically suggests that a series works best for indies. Does it make sense for the first three in the series to form a trilogy? Not always…
A trilogy suggests an entity like the three-movement sonata in music, or the triptych in art. The form must be complete, whereas in a stand-alone the novelist has more freedom to finish where s/he likes, at any point, at any length.
A Relative Invasion is probably the only trilogy I’ll write. It was meant as a novel. I began to write the story of a good-hearted boy, Billy, who was going to need all the resilience he could muster to weather the threat of war, as well as that of his manipulative cousin. A trilogy never entered my mind. I wanted to explore how the emotions that led to WWII might play out in micro, at home in a South London family. This is a story about a life-long rivalry that has lasting effects, just as a war anywhere has a long-term fall-out.

INTRUSION Billy was only five years old at the start of the story. His cousin, Kenneth, was six, but smaller and weaker. Just like a country feeling inferior by size and circumstances, Kenneth resented Billy’s health, strength and size, his more comfortable house, his better toys. Billy’s parents were charmed by Kenneth’s sweet (perhaps cloying) manners and his delicate features. The mother, particularly, had not wanted a sturdy, vigorous boy. How nice to meet one who simply wanted to sit and draw!
By around the third chapter I knew what the ending must be, and I wrote a draft of that. I then returned to where I had left the narrative, concentrating on getting the characters from that point to the end, but by the time I had written one hundred thousand words, Billy was still only seven. At that point I stopped, thinking I had better made the story into two books. Backtracking a little, I wrote a suitable ending to Book One, which came at around seventy-five thousand words.

INFILTRATION. When Book Two reached a similar length, World War Two had just ended, but I was a long way from the climax and culmination of the story. VE Day provided a natural conclusion of Book Two. Billy was then twelve, and cousin Kenneth, thirteen. Adolescence and the terrible austerity of London’s 1940s lay ahead, together with the eventual climax and then fall-out from their life-long rivalry. That was more than enough for an 80,000 word novel.
IMPACT. Book Three had to bring the boys to adulthood, and by the time I’d written to that point, I had rewritten the climax and realized the fall-out deserved a full treatment. The “ending” was written just as I’d planned, except that it now came three-quarters way through the novel.

Billy’s story was now told, the arc I’d envisaged had been completed. I had written a trilogy when I’d intended to write a stand-alone novel. What would I advise if I, or any other writer, was intending to write a trilogy?
Early on, write a time-line.
Put in the historic events, check exact dates of these. Ensure you record each character’s date of birth, location, key events. In a trilogy, you may need to come back to them. Old incidents come back to bite the bottoms of the unwary.
Write your real ending before you get too far into the narrative.
You need to retain a clear sense of where your story is going as you write chapter after chapter.
Mark out how much will happen in each book.
This way you can pace the drama evenly, making sure you don’t stack up the high points too closely together.
The flow of life needs to show:
precursors in Book 1, developments in Book 2, outcomes in Book 3. In music the third part would be recapitulation. Outcomes do have this element: a reworking of earlier events. If there’s a crisis in Book 1 it can resolve, but not really conclude there; longer-term effects should pop up in Books 2 or 3.
There needs to be some sense of linear movement…
even if the books are not arranged in chronological sequence. The reader will want to feel the size of the whole time span by the time s/he reaches the end.
Include several fully-imagined characters.
Three books are too many to focus on just one or two main characters. The work needs other characters with their own concerns for the main ones to knock against and react to. The range of possible interactions gives a more detailed picture of the protagonist(s) and a fuller character development .
Similarly, there needs to be more than one theme.
For instance, the main theme in my trilogy is the far-reaching effects of an ongoing childhood relationship. Connected to this is the theme of coming-of-age, bullying, parenting issues, the subtler effects of war service, and a re-examining where personal responsibility lies.
Although the trilogy will follow one arc, each book also needs its own arc
The three books fell into line with historic events: Book 1 – the tensions leading up to the threat of war until its full onset; Book 2 – the war years; Book 3 – post-war austerity until the war effects in Britain lessened – (“You’ve never had it so good”). Each book contained its own drama; each marked great changes in Billy’s life.
It’s these changes that make for a satisfying place to end one book and start the next.
I’d also suggest the following about a trilogy:
The story has to be substantial.
It has to touch on something in human nature that will resonate meaningfully over the timescale of your three books so that the three properly comprise an entity, not three stories about the same people.
Finally, you need to be a sticker;
someone with a persistent, resilient personality who does not give up what they have started. I wrote these traits into my main character, Billy, and working out his story helped me to stay the course.