Lessons in Chemistry has topped the New York Times Best Sellers since it was published. If you’re a dog lover and fiction fan, you’ve probably heard about Six-Thirty, a rescue, mixed-breed dog, named after the time of the day when protagonist Elizabeth Zott finds him on the street.

After being kicked out of a bomb-sniffing program, the scruffy pup finds his way to Elizabeth, a scientist in the 1950s and 1960s trying to prove her value in a male-dominated profession. Six-Thirty remains a constant in Elizabeth’s story—aside from her passion for science and unwavering confidence in her own talents. Six-Thirty’s smarts match Elizabeth’s as the dog learns nearly 1,000 English words and shares his thoughts and insightful perspective on his family’s adventures.

This year, Six-Thirty and Elizabeth (and the other amazing characters in this book) will be back in action when Lessons in Chemistry, starring Academy Award winner Brie Larson, airs on Apple TV+.

We caught up with author Bonnie Garmus about her knack for naming dogs, Six-Thirty’s rise to fame, and how she hopes his character will bring awareness to dogs’ intelligence.

The Interview Between Bonnie Garmus and Dogster

Dogster: What’s the story behind Six-Thirty’s name?

Bonnie: I thought it would be interesting to have a dog conclude that people and other animals are given names based on what time they become part of a family—because that’s what happened to him. But I’ll add that in chemistry the number six stands for carbon—one of the foundations of life. Meaning Six-Thirty is elemental!

Dogster: Six-Thirty has his own fan base! Were you expecting this level of connection with the dog’s character?

Bonnie: I had no idea Six-Thirty would be so popular. To be honest, when he started to think on the page, I worried. I don’t tend to like magical realism and I shy away from the talking animal trope. But in Six-Thirty’s case, his thoughts didn’t seem magical at all—they seemed normal. He doesn’t talk; he thinks—because all dogs think. In fact, all animals make decisions and solve problems.

But in our society, we tend to judge other animals by human definitions of intelligence, which is a bit ignorant of us. In my book, Six-Thirty turns that around. He questions our intelligence.

Dogster: Is Six-Thirty based on a dog in your own life?

Bonnie: Six-Thirty was based on my previous dog, Friday, who passed away a few years back. The only character in the book based on a real live being. Friday, like Six-Thirty, knew a lot of words. The only difference is, we didn’t teach her those words—she picked them up by listening. When we were transferred abroad to Switzerland, Friday picked German up. Not kidding.

Dogster: Who’s the dog featured in Six-Thirty’s Instagram account? (@sixythirtythedog)

Bonnie: That’s 99 (Bonnie’s current dog)! Poor 99 is a little sick of being mistaken for Six-Thirty—as a retired Greyhound racer, she’s very competitive. But she’s also glad to be part of the movement dedicated to the recognition that dogs actually do think. By the way, I’m terrible at keeping up with Six-Thirty’s Instagram account!

99 was named after my best friend, Helen. When I was growing up, Helen and I loved to watch a show called Get Smart. It featured two spies called 86 and 99 and Helen and I instantly—after about two episodes—made the firm decision to become spies when we grew up. To prepare, we called each other 86 and 99 every day. (For over nearly 50 years!) So, when she died in a tragic accident, I was grief-stricken.

Fast forward 10 years; Friday was also gone, and a 6-year-old retired Greyhound really needed a home. The moment I met the Greyhound, she reminded me of my friend Helen. So, we named her 99 in Helen’s honor. In doing so, I felt like I got a piece of my friend back.

Dogster: What’s your relationship with rescue dogs?

Bonnie: I have a huge soft spot for rescue dogs. We saw that with our dog Friday—she’d been badly abused before she came to us—but we also saw it with our two previous dogs, Astro and Barney, who’d also come from shelters. In contrast, 99 is a purebred—a Greyhound—who came to us through a Greyhound rescue service.

She’d been rejected from a previous home for being “vicious.” When we adopted her—she was 6 by then—she seemed filled with worry and fear, like someone resigned to being unliked. But those fears went away after a few months and she opened up before us and took us in as much as we’d taken her in. She’s very sensitive to human emotion—cannot abide sadness—and tries to help by pressing her (very large) body against the sad person. Kids love her for it and so do I.

Dogster: What can we expect from Six-Thirty when Lessons in Chemistry airs on Apple TV+ this year?

Bonnie: He’s not quite the dog I’d envisioned in the book (in the series he’s a Labradoodle—a breed that didn’t exist at that time) but he’s definitely a presence. It’s a challenge to add a thinking dog to the cast and at this point, I have no idea how it will come off. But the Hollywood people working on the series are the greatest and I feel confident they’ll find a way.

Keep an eye out on Apple TV+ for the new series and follow Six-Thirty’s (99’s) London adventures on social media @Sixthirtythedog