An Architect
What do the terms “Architect” and “Gardener” actually mean? According to George R.R. Martin, in a 2011 interview:
Yeah, to some extent. I've always said there are – to oversimplify it
– two kinds of writers. There are architects and gardeners. The
architects do blueprints before they drive the first nail, they design
the entire house, where the pipes are running, and how many rooms
there are going to be, how high the roof will be. But the gardeners
just dig a hole and plant the seed and see what comes up. I think all
writers are partly architects and partly gardeners, but they tend to
one side or another, and I am definitely more of a gardener. In my
Hollywood years when everything does work on outlines, I had to put on
my architect's clothes and pretend to be an architect. But my natural
inclinations, the way I work, is to give my characters the head and to
follow them.
That being said, I do know where I'm going. I do have the broad
outlines of the story worked out in my head, but that's not to say I
know all the small details and every twist and turn in the road that
will get me there.
Martin speaks in somewhat poetic terms in the first paragraph, but the last one clarifies his meaning. An Architect knows the plot details of the work, whereas a Gardener prefers to let the work develop according to the characters’ personalities and goals.
There is ample evidence, from Rowling herself, that she fits the first of these two categories. She describes her own writing style as one that relies on plotting far ahead. In addition, we have many examples of plot points that she must have known ahead of time.
Her own descriptions of her writing style
J.K. Rowling has stated her outlook on writing is "meticulous" and ordered:
I loathe books that have inconsistencies and leave questions
unanswered. Loopholes bug the hell out of me. I hate getting to the
end of a book and thinking, but if so and so had told Mr Y back in
chapter three, it need never have happened. And so I try to be
meticulous and make sure that everything operates according to laws,
however odd, so that everyone understands exactly how and why.
Note that she does seem to mention that characters’ personalities matter here. Then again, one can carefully script a plot that is still consistent with the personalities of its actors.
Perhaps the strongest piece of evidence is that Rowling herself described her writing process in a style very reminiscent of the Architect. From a 1999 interview:
Q: How does the writing process work for you?
JKR: Because I had all these characters early on, and I felt I knew them
inside-out, I concentrated on putting a massive amount of effort into
each plot. I really love a well-constructed plot. In fact, plot is
such an important framework to me when I write, that before I had
finished the first book, I had plotted all seven books about Harry.
In fact, she is in many ways the opposite of the Gardener. Instead of letting minor plot details flow from the personalities of the characters, she takes the opportunity to arrange them in an interesting manner:
Q: How are you able to pack so many details into a story and keep it exciting?
JKR: If I have worked hard at the plot and it is well constructed and moves at a good pace, then I have the freedom to do the fun stuff
and I can embroider the details within the plot at points where they
create the most interest.
Plot points she planned in advance
If the foremost mark of an Architect is knowing the plot before setting pen to paper, JKR fits the role perfectly.
She planned out many plot points in advance.
For example, she knew the role that thestrals would play when she was writing Goblet of Fire:
At the end of Goblet of Fire, we sent Harry home more depressed than
he had ever been leaving Hogwarts. Now I knew that the thestrals were
coming and I can prove that because they are in the book that I
produced for Comic Relief, Fantastic Beasts and Where to Find Them.
As mentioned in this question, she knew in 1999 that Harry having his mother’s eyes would be important in the later books:
Q: Do you know what Harry’s parents look like?
JKR: “Yes. I’ve even drawn a picture of how they look. Harry has his
father and mother’s good looks. But he has his mother’s eyes and
that’s very important in a future book.”
The whole reason Harry caught the Snitch with his mouth, according to Rowling (via the reputable Melissa Anellion), was to provide motivation for opening it that way in Deathly Hallows.
I had to work quite hard in finding a very particular way for that
snitch to be caught because I knew I was going to do that later;
initially, as my British editor can confirm, I had Hedwig catch that
snitch. She wanted that changed, and I thought, ‘Oh, God, back to the
drawing board.’
Actually that’s what sealed Hedwig’s fate, because the plan was for
Hedwig to open the snitch, because touched it first, but, by making it
Harry, then it was time too kill her earlier. I think she was going to
die anyway, eventually.
There is also substantial in-book clues that certain plot points were present very early on. For example, in the second book Riddle describes himself as pouring his "soul" into Ginny Weasley:
“I grew powerful, far more powerful than little Miss Weasley. Powerful
enough to start feeding Miss Weasley a few of my secrets, to start
pouring a little of my soul back into her….”
Harry Potter and the Chamber of Secrets
Of course, we later learn that the Riddle from the diary is literally a piece of Voldemort’s soul.
Similarly:
“Voldemort put a bit of himself in me?” Harry said, thunderstruck.
“It certainly seems so.”
Harry Potter and the Chamber of Secrets
Of course, there are many other examples, such as Dumbledore’s triumphant look when Harry told him that Voldemort had taken his blood, or the statement that Professor Trelawney had made two correct prophecies.
With multiple statements by Rowling on her propensity to plan many details far in advance, and ample evidence that she did exactly that, it seems clear that she fits squarely in the category of Architect, as described by George R.R. Martin.
