Author Jane O’Connor and illustrator Robin Preiss Glasser are the co-creators of the popular Fancy Nancy picture book series, starring a girl who loves all things fancy and French. In honor of the series’ 20th anniversary, we asked the duo to discuss their friendship and collaboration on the forthcoming book Besties for Eternity—their first Fancy Nancy picture book in seven years.

Jane O’Connor: So it’s been 20 years since the first Fancy Nancy came out. I was still middle aged back then.

Robin Preiss Glasser: I hadn’t gone gray yet. It’s weird to remember that we started out strangers. We have our first editor, Margaret Anastas, to thank for pairing us up.

O’Connor: Now, after creating so many books together, it can feel like we share one brain. I will write certain lines anticipating how you’ll illustrate them, how you’ll milk the most humor from them.

Glasser: And we trust each other enough that I can show you when a sentence isn’t needed anymore because I’ve incorporated the joke in the drawing.

O’Connor: Yes, I’m extraordinarily gracious about that.

Glasser: Most of the time.

O’Connor: I think the trick for both of us is making sure that the character of Fancy Nancy doesn’t cross the line into bratty territory. In our new book, Besties for Eternity, Nancy’s bedazzled by a new friend, from Paris, no less! And, without thinking, she’s hurtful to Bree, her bestie-since-forever.

Glasser: I needed to show through body language how much Nancy regrets her behavior.

O’Connor: From your many years as a professional ballet dancer, you know exactly how to do this.

Glasser: Hand gestures, drooping shoulders, a tilt of the head, for instance, can telegraph so much.

So, Jane. By now I know how you came up with the idea for Fancy Nancy—

O’Connor: Yeah, you’ve heard the story many, many times. I was making dinner for my family when all of a sudden the name Fancy Nancy flew in my head. I started writing the first story that night. I wanted her to be a little girl who made her entire world fancy herself—DIY. It was not just about clothes and décor. It was about using fancy words and holding a pinkie up when drinking a cup of tea.

Glasser: I was that DIY child! I had a troll doll with hot pink hair that I made tutus for and a boa and tiara. I came up with the look of Nancy with my troll doll in mind. And I knew she would just love ballet and walk around on her toes. But for me, I needed to show that she was “fancy on the inside.” She has a big heart.

Jane, were you like Fancy Nancy when you were little?

O’Connor: Not really. But when my grandma and great aunts would come to visit on Sundays, I’d come galumphing out to greet them in a pair of my mom’s high heels, a tutu, a red satin cape and I’d be dripping with jewelry. I wanted to look glamorous for my guests.

Glasser: After a seven-year break, was it hard getting back to writing about Fancy Nancy?

O’Connor: Not really. By now, the character is lodged in my head. Much harder was coming up with the right story, until it hit me that I had never done a book about friendships.

What about you, Robin? Do you find yourself repeating illustrations you’ve done in earlier books?

Glasser: No. Because Nancy is something of a drama queen, there are endless ways to translate her onto the page. Also I love coming up with new, over-the-top ensembles.

O’Connor: And now with Besties for Eternity done, we get to the most fun part: going to bookstores and schools and sharing the story with kids.

Glasser: What’s the most memorable thing a child has come up and said to you?

O’Connor: Once, while signing a very fancy little girl’s book, she whispered how she preferred to call her underpants her “privacy shorts.” That slayed me. And you?

Glasser: What I wonder is, how many sobbing, disappointed children will come up to us, as they have before, demanding to know where the real Fancy Nancy is?

Fancy Nancy: Besties for Eternity by Jane O’Connor, illus. by Robin Preiss Glasser. HarperCollins, $19.99 Sept. 16 ISBN 978-0-06-341122-7