While the Jewishness is not only upfront but subtle, David says that she "didn't want to write about overt 'Jewish' topics like antisemitism because they weren't things that affected my kids directly.
‘Suddenly, I was talking to my kids all the time about antisemitsm’
"I finished the first draft of the book, and then the Gaza conflict happened, and the attacks in Paris. Suddenly, I was talking to my kids about antisemitism all the time. It seemed to me all the more important to have a book about normal Jewish kids doing normal things, read by Jews and non-Jews alike.
"The book is about love, and the rules and conventions surrounding love - whether it's laws about who you can love, or romantic conventions about making a move on someone else's boyfriend. As Judaism is based on a legal system, this seemed a good fit. I think Jewish parents might find this book interesting, as well as Jewish teens. There were a lot of moments when I thought: 'What would I do if my kid…' when writing this book."
When Sarah J. Maas had a chance to put a note in the Western Wall during a Birthright tour, her prayer was for something in the world-peace category - and to become a published author.
She had already written the first three books of what was to become the New York Times bestselling Throne of Glass fantasy by the age of 16, "before, after - and sometimes instead of - homework".
Raised in New York by her Catholic mother and Jewish father, Maas attended Hebrew classes and was batmitzvah but really connected with Judaism at college, when she met future husband Josh - "he was president of the college's Hillel and he made Judaism cool for me".
Birthright reinforced this: "The Wall on Shabbat was one of the coolest experiences, full of joy and energy. I left Israel overflowing with pride. It's a magical, welcoming place."
A very different wall features in her new book, A Court of Thorns and Roses, (Bloomsbury, £7.99). Following an invasion of faeries (the spooky, mythological sort, not the wispy tinsel-and-tutu type), mortals have been left with a tiny territory, sectioned off by the wall - on the book's map it looks like a tiny slice of southern England below Wiltshire - where they live in terror of incursions.
A mere skinny girl, Feyre, hunts to feed her ungrateful sisters and lame father. But when she slays a magical creature, she is forced to repay the scary faeries by living on their side, with a shape-shifting man-beast. A more grown-up, sometimes "steamy" take on Beauty and the Beast, Maas's book draws on a range of folklore, from English to Hindu.
"My parents told me any and every fairy-tale from all around the world," Maas says. "I usually gravitated towards ones with interesting, strong heroines."
A real-life role model is her grandmother Camilla, who was born in Frankfurt, rescued from the Nazis by a Belgian Catholic family and fled the occupation under gunfire, eventually being evacuated to America.
Maas's great-grandfather survived Auschwitz and Buchenwald; her great-grandmother perished in Majdanek. Maas and her husband were proud to entertain Camilla to their first Seder in their Philadelphia home this Pesach.
Family loyalties and sharing good times around a tableful of food are also important in A Court of Thorns and Roses - although the faerie conquerors have banished all gods.
"It's interesting to write about a world that had got rid of its gods - that might be why Feyre's world is so fractured and bleak," says Maas.
We will see a more overtly Jewish moment in Queen of Shadows, the next Throne of Glass instalment, out in September, when heroine Celaena visits her ancestors' graves and lays stones.
As Maas happily juggles working on the two series, demand for such stories of imagined worlds continues to grow - partly, she suggests, in response to post-9/11 terrorism.
"We find ourselves attached to fantasy worlds sometimes when it's hard to process what's going on in our world," she says. "It's reassuring to see the good winning."
