Rick Riordan was greeted like a rock star as he came on the stage at Saturday’s Boston Book Festival. A crowd, filled with young and old fans alike, cheered for the author who’s created best-sellers for nearly two decades.

Riordan is most famous for his “Percy Jackson & the Olympians” fantasy series about a young boy who discovers he’s actually a demigod, and must go on quests to fight some of the biggest, baddest legends in Greek mythology, while attending Camp Half-Blood, a training facility for other kids like him.

Ahead of his keynote address at the festival, Riordan sat down with GBH News to talk about his newest projects and his appreciation for his dedicated readers. The line to see him was wrapped around the block of the Old South Church and was so long that some people had to be turned away, a reaction that Riordan said “always amazes” him.

“I had a lot of years there, where I was writing books and nobody would show up for signings," he said. "And that's pretty typical for a lot of writers. So, I don't take anything for granted. It's always an honor to have people actually show up to hear about books. I think that's always a great reason to celebrate.”

Riordan has penned multiple book series that retell famous mythology, including “The Heroes of Olympus,” “The Kane Chronicles,” “Magnus Chase and the Gods of Asgard,” “The Trials of Apollo” and more.

But it's the character of Percy Jackson that has enchanted readers for years. The books spawned two movies a decade ago (that Riordan himself disavowed). Now, the series is being turned into a TV show premiering next month on Disney+, with Riordan and his wife Becky serving as executive producers.

“Everything that happened, we were part of it,” he said about the new show. “And I'm excited mostly because the eight episode season gives us time to explore the whole plot of ‘The Lightning Thief' and do justice to a lot of scenes that have never been adapted before. And I think, especially, readers of the books will enjoy seeing those come to the screen.”

And Percy’s world continues to grow. In September, Riordan released “The Chalice of the Gods,” the first of a three book series that sees Percy Jackson as a high school senior, no longer trying to save the world — but trying to get into college. When the school of his dreams, New Rome University, requires recommendation letters from three gods, the character must go on quests for each of them.

“[Percy] is sort of outside of time,” Riordan said. “He's not tied to any particular year or decade, and that was mostly on purpose because I know that there are always new generations of young people coming up and they all need great books, and I hope that they'll continue loving the Percy Jackson series. And from what I've heard, that's been the case. It's really wonderful to hear from readers who are eight years old or eighty years old, and they can all find something to enjoy in the books.”

It was important to Riordan to stick with the middle grade genre — aimed at kids eight to 12 — that he’s always written in, even though Percy Jackson’s character has started to grow up.

“I'm biased because I was a middle school teacher for many years, and I really do think that's a critical age,” he said. “That's the age typically where kids become readers or they don't. They're changing in every possible way. They're finding out who they are. They're exploring the world, learning about it in new ways. And so we have to provide kids of that age an opportunity to love books.”

Riordan is passionate about readers having access to stories that reflect their own lives. He wrote Percy Jackson as a way for his son, who has ADHD and dyslexia, to feel seen. Percy too has these disorders — but in the book, they are explained as something all demigods have — unable to focus because they are meant to be fighting monsters and having difficulty reading because their brains are wired to understand ancient Greek.

At a time when book challenges are rampant across the U.S., including some against his own, Riordan says he remains committed to representation.

“We've got all kinds of readers in the world and we need all kinds of books in the world,” Riordan said. “Every reader deserves to see their experience represented. The books have to be mirrors for experience, and they have to be windows into other worlds... So I think the answer is always read more, not read less.”

Riordan says readers often ask him to tackle other cultures' mythologies in new books, but he realized that authors from those cultures would tell the stories better than he could. He said that was the idea behind Rick Riordan Presents, an imprint where he promotes and publishes other authors’ books featuring a wider range of mythological stories.

“It's important for all kinds of kids to know they can be heroes of stories, too,” he said. ”It's very empowering for a young reader to see a kid on a cover that looks like them. It's even more empowering to know that the author comes from a background similar to theirs and looks like them. That opens up the world of story, I hope, for everybody.”

Disclosure: GBH was a presenting partner for the 2023 Boston Books Festival.