Lizzy is a sweet nine-year-old girl who truly believes in fairies. She is extremely aware that it is the fairies that bring about the changes of seasons, and she really loves spending time with her father of her, but in this regard initially her father is a bit ignorant and stubborn about what she really matters. Towards the end of the film she proves to be very sociable and protective of her friends.
Lizzy is first seen with her father going home for the summer. Lizzy's father never listens to her and always cares about her only to her scientific discoveries, for this reason Lizzy feels very lonely, but her dreams about the fairies that she adores and believes in them since she she was born makes her happy.
On that same day, Lizzy builds a fairy house hoping to meet a real fairy. Tinker Bell and Vidia find the house that Lizzy built and Tink wants to go right in, much to Vidia's disapproval. To teach Tink a lesson, Vidia with her wind power closes the door trying to scare Tink without success. When Lizzy arrives, Tink doesn't have time to escape and is found by Lizzy and taken to her house. Vidia thus runs to warn the other fairies about what has happened.
Meanwhile, Lizzy decides not to show Tink to her father and the two of them soon become great friends, and Lizzy soon asks her to teach her all about fairies (about how they are born, what they do, how they are made ...), and they play together, finally Lizzy he feels he has a true friend next to him. That night while Lizzy is asleep, Tink takes a tour of her house and fixes a few things and in the meantime decides to free the butterfly captured by Dr. Griffiths. However, this leads to Dr. Griffiths' nervousness who the next morning immediately blames Lizzy for the butterfly's disappearance.
To console Lizzy, Tink spreads the Pixie Dust on her and makes her fly as she always would have liked. When Dr. Griffiths hears the noises he goes into Lizzy's room and starts scolding her again for believing she's having a tantrum, and when Lizzy tries to explain to him that fairies exist her father still doesn't believe her and immediately intends to stop them "absurdity". Tink, being sick of her doctor, reveals himself to him (even if what you hear about her is only the sound of a bell) and begins to attack him to her shock.
Enchanted by Tink Dr. Griffiths tries to capture her, but in her place he takes Vidia who leads Tink astray, then rushes to London to take her to the museum, and Lizzy's efforts are of no use. After Tink reunites with her friends, they dust Lizzy to fly to the rescue, Lizzy is unsure of this because she only flew to her room but to get to London, but she is reassured by Tink.
After Tink tampered with Dr. Griffiths' car and the latter tries to walk away, she Lizzy stops him before he can enter the museum. As soon as Dr. Griffiths sees his daughter flying, he is shocked and says that he cannot understand how this is possible, but after Lizzy finally gets him to hear him, he realizes his mistakes, and apologizes to Lizzy. and promises her that from now on he will never doubt her again, and after that Lizzy hugs him happily.
Lizzy then frees Vidia and her father is sprinkled with Pixie Dust and they all go home together, and during the flight they trigger Big Ben (which Dr. Griffiths would always like to do).
The next morning Dr. Griffiths finally forgets her work for a while and she along with him, Tink and the other fairies enjoy a basic party at a Pic-Nick as the little girl would always like. In the finale, it is seen that Fawn, Silvermist, Rosetta and Iridessa give her a crown made of flowers and Blaze and Cheese offer her tea.
Lizzy is now happy that she can spend time with her father after a long time and she knows that from now on she can always count on Tink and her friends.
In some ways, Lizzy is similar to Wendy Darling from the original Peter Pan:
They both have fathers who are stern and ignorant and say that things like Peter Pan and fairies are just nonsense , but in the end both girls manage to make them think (a pirate vessel sailed by Peter Pan for Mr. Darling and fairies for Dr. Griffiths).
Both are nice to everyone and are great friends with Tinker Bell (although Tink has had a little rivalry with Wendy).
Lizzy was mentioned in Secret of the Wings by Tink when referring to her twin sister Periwinkle.