The author of The One and Only Ivan revisits the animal comrades from that 2013 Newbery winner in The One and Only Bob, due on May 5 with a 500,000-copy first printing. Katherine Applegate’s sequel is narrated by Ivan’s best friend, Chihuahua mutt Bob, a tough-talking but soft-hearted former stray who admits to becoming a bit spoiled since being rescued by a caring family. Bob’s favorite pastime is visiting Ivan in the wildlife sanctuary where he now lives with Ruby, the young elephant whom the gorilla and dog befriended in the previous book. Applegate told PW about her motivation for continuing the tale of this trio in her new novel, which interlaces themes of friendship, loyalty, trust, and—most pointedly—survival.

Did you know when you finished writing The One and Only Ivan that it might have a sequel?

No! I had no intention of writing a sequel—which may explain why it’s been eight years since that novel came out. When I finished writing Ivan, it felt like a very complete story. And also, maybe because I’ve written so many series books [Animorphs; Endling], I really love writing single titles. But on every school visit I make, without fail kids will say, ‘There’s got to be a One and Only Bob!’ Occasionally someone will suggest I write a book about Ruby—but universally they ask for Bob.

Was it at all intimidating tackling a follow-up to a novel that won a Newbery?

I guess I went into it thinking that sequels are almost always disappointing on some level. When readers have a positive experience with a book, in a sequel an author might evoke that experience but never duplicate it. I resisted writing Bob for a while, knowing from the start that it might be hard, since Bob’s voice is hugely different from Ivan’s. At the same time, I knew that Bob’s was a fun voice and one I was familiar with. And I of course thought about all the sequels that have been written that do really work.

Once you decided to give the novel a go, was it easy to slip back into the world of Ivan, Bob, and Ruby?

Yes! This was a really fun book to write—and I don’t always feel that way. I do like revisiting characters. In a way, it is so much easier than creating new characters. I think what I most liked was going back to that weird, first-person narrative style. It lets me write in small spaces, and cherry-pick the best scenes to include. It’s a writing style I am very comfortable with and I was itching to do it again. I think maybe I’m a frustrated poet!

I knew that Bob’s voice and story would be different than Ivan’s. Ivan’s voice of necessity is philosophical and poetic—he uses lots of metaphors. Ivan was essentially imprisoned, and his, by definition, was going to be a quiet story. But Bob’s story is very action-focused, and the characters are out in the world, so I was able to let them cut loose, which was fun. And in terms of his voice, Bob is, well, Bob is Danny DeVito! As I was writing, I kept hearing his voice, and as it turns out, DeVito is recording the audio book, and is the voice of Bob in the upcoming Walt Disney Studios film!

Was it a challenge to cast Bob in a new role and light?

Bob was an old friend, and his story came easily to me. Though I was a bit worried, since I’d used him for comic relief in Ivan, and it was very different to focus on him entirely. I had to delve into his dark side. Bob is still a look-out-for-numero-uno guy, but here he’s not the comic relief in the corner. He sees himself as a coward, since he was too terrified to go back and rescue his sister, Boss, when they were abandoned by the roadside as puppies. He was just a puppy, after all, but in his mind, he failed, and that haunts him. Bob is working through it, but he has to learn how to forgive himself—and the humans who abandoned him and Boss. I open the novel with the quote, “To err is human; to forgive, canine.” Dogs are so tolerant as a species, and for Bob not to be that kind of dog made him more interesting to write.

Bob now has a loving adoptive home, and Ivan and Ruby are living in a wildlife sanctuary rather than a cage in a shopping mall. Yet Bob reflects that he “would give up a mile-high-pile of bacon cheeseburgers” to see Ivan “deep in the jungles of Africa” and Ruby “running across the savanna with a herd of elephants,” but concedes that they all know “it ain’t happening.” What do you hope kids will take from that dose of realism?

Yes, the characters’ situations are better, but not perfect by any means. Bob wants his friends to be happy in the wild, where they were born. When I do school visits, I am always impressed by how kids understand that nuance better than adults. They seem to understand inherently that, since humans have so extensively encroached on wild animals’ worlds, we have an obligation to care for them, but that we don’t always live up to it. As far as I know, there are no gorilla sanctuaries in the U.S., but there are wildlife sanctuaries—some of which are good, and some not so. I like to think that Ivan and Ruby are in a good one, and I hope that’s the impression I left.

The One and Only Bob has garnered some positive pre-pub reviews—including a starred one from PW. Have you had an enthusiastic response from other early readers?

I have. It is so good to hear from teachers who have read the novel and liked it. I’ve also heard from a handful of teachers who said they are now reading it at home to their own kids, who are enjoying it. Kids are so open-minded, and love discovering new books with new characters, but they are also willing to go back and hang out with old friends, like Bob, Ivan, and Ruby. That makes me happy, since I feel the same way!

The One and Only Bob by Katherine Applegate, illus. by Patricia Castelao. HarperCollins, $18.99 May 5 ISBN 978-0-06-299133-1