First, define the goal or conflict for the story involving the free characters. Let's say you have a group of free characters like a group of rebels. Decide what they are fighting against, like an oppressive regime. Then, develop their relationships within the group. Some might be leaders, some might be strategists. Detail their journey towards achieving their goal, including setbacks and victories. This will make for a rich and complex story.
Without having read the book, it's difficult to determine the main characters precisely. But it's possible that there are characters from diverse backgrounds. For example, there could be a working - class character who dreams of financial freedom, and a creative character who desires artistic freedom. These different characters would then interact and their stories would unfold in relation to the overarching concept of freedom.
Myths and legends are also full of great free characters. For example, Odysseus from Greek mythology. His long journey home after the Trojan War, facing various monsters and challenges like the Cyclops and the Sirens, can be a great source for an epic story. Fairy characters such as the Tooth Fairy can also be used. It's a simple character that children are familiar with and can be given different personalities in your story. Additionally, the Wizard from 'The Wizard of Oz' is a great character. He is mysterious and powerful, and his relationship with Dorothy and her friends can be explored in many different ways.
Some popular ones are the characters from the open - source anime project 'Anime Open Source'. They are free to use for various creative works including stories. There are also some simple, basic anime - style character templates available on sites like Canva. You can customize them a bit to fit your story needs.
One way is to give them new backstories. For example, if you're using the character of Snow White, instead of the traditional story, you could make her an adventurer who was cursed to look like she was poisoned, and she has to go on a quest to find the cure. Another method is to change their personalities. Take Pinocchio, for instance. Instead of being a naive puppet who just wants to be a real boy, make him a cunning character who uses his wooden body to his advantage in a world full of humans. You can also put them in different settings. Imagine Little Red Riding Hood in a modern city, dealing with traffic and strangers instead of the forest and the wolf.