Over the course of the novel, Winnie has changed to become more independent. When we are introduced to Winnie, she chafes against the restraint that she feels has been implemented on her by her hovering family members.
"See?" said Winnie to the toad. "That's just what I mean. It's like that every minute. If I had a sister or a brother, there'd be someone else for them to watch. But, as it is, there's only me. I'm tired of being looked at all the time. I want to be by myself for a change."
She longs to do something important and make her mark on the world, yet she feels incapable of doing this while living where she lives. Winnie actually feels the only alternative is to run away:
"I'll never be able to do anything important if I stay in here like this. I expect I'd better run away."
Unfortunately, Winnie doesn't have the courage to actually run away. She does get brave enough to leave the house early one morning and go into the nearby woods. It's here that she runs into the Tuck family, and her adventure with them begins. She learns their secret, and she learns the importance of keeping that secret from the general public. That knowledge, coupled with her positive feelings about the Tucks, gives her the courage to sneak out of her own house later in the story to help rescue Mae. She does this knowing that she will be caught and will suffer the consequences; however, she now has the courage and independence to stand up for what she believes in. She takes action and does something important.