How do Rowling and her collaborators Jack Thorne and John Tiffany use geometric patterns in the play Harry Potter and the Cursed Child?
First, the main geometry in the play is a pair: Albus and Scorpius.
Whether they are a romantic or a non-romantic pair is in the eye of the beholder but they are not clearly romantic. For a time this pair grows into a trio--Albus, Scorpius, and Delphini--with at least some Albus/Delphini romantic subplot. When they use Polyjuice Potion to infiltrate the Ministry, they impersonate the original trio, Harry, Ron, and Hermione.
But when it comes to the actual Harry, Ron, and Hermione, they are not presented as a trio. The quartet geometry--Harry/Ginny and Ron/Hermione--is much more prominent in the play than it is in the book series.
There are lots of scenes with Harry and Ginny alone together or Ron and Hermione alone together, and not a single scene with just the Harry-Ron-Hermione trio (except for the fake Polyjuice version). Let me repeat that last statement, because I couldn't believe it until I went through the entire play and checked it carefully: There is not a single scene in Harry Potter and the Cursed Child that features the Harry-Ron-Hermione trio alone together.
Whether this change came from Rowling at all or only from the Thorne/Tiffany duo, and whether they saw themselves as correcting a flaw in the books or just did this naturally, isn't clear, but it is certainly a striking departure from the original series. Perhaps we should simply interpret it as an accurate portrayal of the dynamics of two married couples.
Then, by the time we get to the action climax, the characters have formed themselves into a five-guys-and-two-token-gals geometry:
I must admit I rather resent the lack of female characters, though I suppose I ought to give them credit for Delphini. And certainly it is nice--and different from the books--to see an actual female Minister for Magic and Hogwarts Headmistress for once.
If we were wondering whether The Cursed Child would reflect Rowling's later doubts about the Ron/Hermione pairing, the answer is mixed. The play treats the Harry/Ginny relationship as a given but interrogates the Ron/Hermione relationship. The three relationships of most interest in the play are Harry-Albus, Albus-Scorpius, and Ron-Hermione. Of these, the first two are mostly new to the play but the third is a re-examination of the original books. So we can say that Ron/Hermione is treated as potentially problematic but in the end it is triumphantly endorsed--as are the other two relationships, resulting in an all-around happy ending. It is not surprising that Rowling's collaborators, Jack Thorne and John Tiffany, would have been reluctant to contravene any element of her previous work but it seems to me that they appreciated the Ron/Hermione pairing for its unique blend of humor and passion and wanted to exploit that in their play. Anyway, it gives the Granger-Weasley family a subplot that would otherwise be lacking since their relationship with their kids (or kid, since Hugo doesn't seem to exist) is almost completely ignored.
Some writers are drawn to including romance in their works and others aren't. It seems clear that Jo Rowling is. All of her works except for The Casual Vacancy have love stories which seem to be moving toward happy endings and even that book contains many romance-related subplots. I have already pointed out that the quartet geometry in Fantastic Beasts gives us more romance than most adventure movies have.
As long as she continues to write love stories Rowling will be dealing with the geometry of romance. So far, since stepping out with a somewhat unusual geometry in the Harry Potter series, she has played it safe with conventional pairs and quartets. But I expect that to change and for the geometry in both of her series to become more complicated. In the Cormoran Strike series it is possible that Shanker and Elyssa will become a secondary pairing. In the next Fantastic Beasts movie we already know there will be a third pair, Theseus Scamander/Leta Lestrange, which already crosses with Newt/Tina. Both series have a lot of planned installments still to come, so who knows what we will see in the future?
Rowling has, alas, not gifted us with another pair of bickering lovers. I don't know if she has been scared off from this trope, or if its turn simply hasn't come around again in her palette of paints. We do know that she has NOT been scared off from using jealousy as a romantic indicator, since she uses it heavily in the Cormoran/Robin romance. She even, at least to the extent that she participated in the Cursed Child play, considers jealousy a possible instigator of romance because Ron and Hermione didn't get together without Hermione going to the Yule Ball with Krum and Ron's subsequent jealousy. Jealousy can start a relationship another way: it seems to me that Matthew's jealousy of Strike was the first thing that prompted Robin to see Strike as a possible romantic partner.
Another thing that Rowling is said to have done "wrong" in writing the romances in the Harry Potter series has to do with point of view. Harry is the top of the regular triangle not just because he is the title character, or the Chosen One who is fated to defeat Voldemort and save the wizarding world. He is also clearly at the top because he is, with rare exceptions, the only point-of-view character. We (usually) see only what he sees, know only what he knows, and are privy to his thoughts. He has much more page space, though not necessarily more dialogue lines, than any other character.
The Ron and Hermione romance across the bottom of the triangle is much more prominent (in page space, lines of dialogue, etc.) than Harry's romance with Ginny, but neither Ron nor Hermione is a point-of-view character. This made it possible for many readers to refuse to understand that Hermione and Ron were being written as a romantic pairing and makes it more difficult for readers to identify and empathize with their feelings. With the Harry/Ginny romance, we see Harry's romantic thoughts but not Ginny's, leading some readers to interpret her feelings in extremely unsympathetic ways, arguing that she was only attracted to Harry because of his fame or that she had a long-time plan to trap Harry into marriage because he was rich or some other such nonsense.
A romance where we see only one person's point-of-view was very common in the time period from about 1900 when omniscient narrators fell out of fashion until about 1975 or so. At that time it became common for romance novelists to alternate between the hero and the heroine as the point-of-view character and that structure is now almost universal in the genre. A similar expectation seems to be shared in the wider culture. Perhaps in the old days it would have been enough for us that Harry wanted Ginny and he successfully won her, but readers now (especially female readers, I think) want to see Ginny's side of the story as well, both to make sure that she "deserves" Harry and so we can empathize with her feelings.
There was a tendency in older romance novels for the hero to have a monologue reveal at the end of the story, somewhat like a villain monologue, where he explained all his actions during the courtship, proving that he was worthy and loved her all along. Rowling did a tiny bit of this when Ginny explained to Harry that Hermione had advised her to move on and date other boys to get over her shyness with Harry, but that she had never lost interest in him, but this clearly wasn't enough for many readers. Nor did she give us many conversations between Harry and Ginny to show us how their relationship works.
The bottom line is that the Harry/Ginny romance is not given very much page space. This isn't something I mind; I have read many novels where the romances are given much less. One example that leaps to my mind is Georgette Heyer's mystery novel No Wind of Blame, where the point-of-view heroine is suddenly proposed to at the end of the novel by a very minor character whom we had no idea she cared for, or vice versa. This follows many pages where two secondary characters--the heroine's possible suitor and her younger relative--fall in love in an entertaining, rather bickering-lovers way. Compared to that novel (which I love), the Harry and Ginny story is a soppy, sentimental love-fest.
But the Cursed Child play gives them much more. There are seven scenes in the play with Harry and Ginny conversing alone, plus quite a few more where they are interacting as a couple with characters like Draco, McGonagall, and Albus. Rowling has also corrected this problem in Fantastic Beasts. Already in the first movie, she has given us several flirtatious or serious romantic scenes between Newt and Tina and Jacob and Queenie. The Cormoran Strike books go all the way: Robin is a point-of-view character like Cormoran, and we have many, many pages of Robin and Cormoran talking to each other, thinking about each other, etc. We know exactly what they do (and don't) see in each other and precisely how their slow romance is progressing.
Somehow, though, as much as I love Cormoran and Robin, and as much as I'm eager for the fourth Cormoran Strike book and the second Fantastic Beasts movie, I'd rather watch Ron and Hermione bicker just one more time.
Part One: Introduction Part Two: Pairs Part Three: Quartets and More Part Four: Trios--