If you’ve ever seen a child tear through the Magic Tree House book series or tote around a battered copy of Diary of a Wimpy Kid, you’ve witnessed the power of a great series character.
For children, characters in book series aren’t just fictional—they're companions, role models, and even imaginary best friends.
As writers of children’s books, understanding what makes these characters so enduring can help us craft stories that resonate deeply and keep young readers coming back for more.
The Power of Familiarity
One of the biggest reasons children love book series is the sense of familiarity. Kids thrive on routine and predictability, and when they return to a character they know, they’re stepping into a world where they feel safe, welcome, and in control.
Think about Junie B. Jones or Dog Man—these characters carry the story and the reader's trust.
When writing a series, consider how your character welcomes the reader. Are they consistent in voice, attitude, or appearance? Even if they grow over time (which, depending on the length of the series, they should), their core traits should remain intact.
If Judy Moody is moody in Book One, she can’t suddenly become cheerful and serene in Book Five without a believable reason. That familiarity is part of the appeal.
In The Adventures of Planetman, one of Thomas’ sidekicks, Luke, is always hungry and thinking about food. This trait is carried through the series, as are the superheroes’ superpowers.
If Thomas’ ability to fly was switched to super strength and Luke’s super strength was switched to flying, the fantasy world would come crashing down. Unless a reason for the switch was brought to the young readers' attention.
A Strong, Memorable Voice
Children’s series characters often have distinct voices—not just in how they talk, but in how they think, act, and interpret the world.
Ramona Quimby sees things differently from Clementine. Percy Jackson’s sarcastic, anxious narrative voice is much different from Geronimo Stilton’s more prim and panicked tone.
When done right, the voice makes even an ordinary plot feel personal. If you’re writing a series character, try journaling as that character. How would the character describe a thunderstorm? A new kid in class? A favorite video game?
Voice is where character and tone meet. It’s what allows readers to hear the character even when the book is closed. It's what creates memorable characters.
Growth That Doesn’t Break the Mold
Here’s where things get tricky: readers want both consistency and growth. A series character needs to evolve just enough to stay interesting but not so much that they become unrecognizable.
Harry Potter is a good example. He changes—from a wide-eyed boy to a determined teenager—but he’s still Harry. He still has that sense of justice, that loyalty to friends, that frustration when adults don’t listen. The trick is to allow growth that feels natural and age-appropriate rather than forcing your character into dramatic shifts.
Two helpful questions to ask: what is your character learning across the series? Is each book a new adventure and a new lesson? That arc—especially when tied to development—makes your series more meaningful and memorable.
Is growth an absolute must?
In the Planetman series, there is no character growth. The books have the same characters in new adventures with new lessons. They’re written to teach children about the environment. This type of series is considered a static series.
Supporting Cast and Worldbuilding
Series characters don’t live in a vacuum. Often, it’s the supporting cast and world that keep readers coming back.
Whether it’s the friendship rivalry in Ivy + Bean, the mythology-rich world of Percy Jackson, or the neighborhood setting in The Baby-Sitters Club, recurring elements help anchor the character’s journey.
Pay attention to the relationships in your series. Do characters return in meaningful ways? Is there space for new characters to appear without losing the flavor of the world?
Think of the supporting cast as part of the emotional fabric your reader connects to—not just filler.
Stakes That Stay Relatable
In adult fiction, stakes often revolve around life-or-death scenarios. In children’s books, especially series, the most effective stakes are emotional and personal. A lost toy, a failed spelling test, moving to a new neighborhood, a new baby in the family—these situations may seem small, but to a child, they’re enormous. And when a character is going through the same thing, it validates the reader’s feelings.
Your series’ main character doesn’t need to save the world in every book. But they do need to face situations that matter to your reader. The more your character reflects real childhood concerns, the deeper the connection will be.
Humor, Heart, and a Little Bit of Quirk
Most successful children’s series characters have a dash of humor, a dose of heart, and, often, a quirky trait or two. Whether it’s Dory Fantasmagory’s wild imagination, Hank Zipzer’s dyslexia-driven antics, or Captain Underpants’ absurdity, these traits help characters stand out and stay lovable.
Ask yourself: what makes your character fun? What makes them memorable after the book ends? A strong character isn’t always the smartest or the bravest—but they’re always the one readers enjoy hanging out with.
Summing It Up
Writing a children’s book series character isn’t just about creating a protagonist who can carry a plot; it’s about building a personality that young readers want to return to again and again.
Think consistency, voice, growth, relationships, relatable stakes, humor (whether a sprinkle or a flood), and a touch of the unexpected.
When done right, your series character becomes more than just a name on a page. They become the reader’s friend. And for a child, that’s the most magical reading experience of all.
