Cleo Sertori

Ceo Sertori is one of the main character of H2O: Just Add Water. Cleo is a mermaid with the power of hydrokinesis and Aerokinesis, the daughter of Bev and Don Sertori and older sister of Kim Sertori. She was portrayed by the starring cast member Phoebe Tonkin.

Early Life
Cleo was born to Bev and Don Sertori and later she had a younger sister Kim. She never learned how to swim and was affraid of the water. She also at some point befriended Emma Gilbert.

Becoming a Mermaid
Cleo was tricked by Zane Bennett that trapped her while trying to repair his boat. Rikki jumped to the boat and fixed it, later Emma joined them. The three girl got trapped on the ocean because the boat was out of fuel and they were very far from land.They paddled to a close island, the Mako Island. There they tried to call someone but the signal was weak so they tried to fin a place where they could have signal. They felt into a cave where they saw a Moon Pool. The pool was connected to the ocean and the three girls jumped to the pool, at the same time the full moon was over the pool and they saw it bubble. Later they were rescued by the police. In the morning Cleo was on the bath when appeared a tail. Later she talked to her friends learning that she wasn't the only one affected.

Keeping the Secret
Cleo and the girls agreed to protect the secret about mermaids, however, Cleo wanted to tell Lewis about the powers and that he could find a way to help them. Rikki and Emma disagreed. Later Lewis found out she was a mermaid when Zane and his friends dropped her in Miriam's pool and he helped her and told her that he would keep the secret.

Saving the Turtles
Cleo was affraid of the water and her powers, she avoid it all the time. She thought that her father was capturing turtles and later found out that wasn't him, she lost her fear and saved the turtle, she got trapped in the net when she saved a turtle. She was under water during a lot of time until her friends saved her and from that day she accepted the fact that she was a mermaid.

Getting a Job
Cleo was trying to live a normal life and got a job at the Marine Park as dolphin feeder. When she was working, she got water on her a woman helped her and when talked to her she knew that the woman knew something. Later she went to Emma's party and got water on her, she hide her tail from the other girls and in the end she received a present from Emma, the necklass that she found out in Mako's Moon Pool. In the next day she talked to the woman she talked in the previous day and she told her that the necklass belonged to her friend Gracie and that she lost it in the Moon Pool.

Powers
Cleo possesses all powers of a mermaid.
 * Hydrokinesis: Cleo possesses the ability to control water. She can make the water float and change it. She can also manipulate water when she is freezed.
 * Aerokinesis: Cleo possesses the ability to control air. She can make things and even people float and can control the weather when combined with her friends powers. She got this powers when her powers were amplified by a rare planetary alignment.

Personality
Cleo is a smart, selfless and friendly person. She like to have new friends and does anything to keep them safe and also to keep her secret.

H2O: Just Add Water
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Season One

 * Metamorphosis
 * Pool Party
 * Catch of the Day
 * Party Girls
 * Something Fishy
 * Young Love
 * Moon Spell
 * The Denman Affair
 * Dangerous Waters
 * The Camera Never Lies
 * Swink or Swim
 * The Siren Effect
 * Shipwrecked
 * Surprise!
 * The Big Chill
 * Lovesick
 * Under the Weather
 * Bad Moon Rising
 * Hurricane Angela
 * Hook, Line and Sinker
 * Red Herring
 * Fish Out of Water
 * In Too Deep
 * Love Potion 
 * Dr Danger
 * A Twist in the Tail

Season Two

 * Control
 * Fire and Ice
 * Double Trouble
 * Emma Rebel
 * Hocus Pocus
 * Pressure Cooker
 * In Hot Water
 * Wrong Side of the Tracks
 * Riding for a Fall
 * Unfathomable
 * Treasure Hunt
 * Fish Fever
 * Camping at Mako Island
 * Cleo vs. Charlotte
 * Irrestible
 * Visions
 * Moonstruck
 * The Heat Is On
 * The Gracie Code, Part One
 * The Gracie Code, Part Two
 * And Then There Were Four
 * Bubble, Bubble, Toil and Trouble
 * Reckless
 * Three's Company
 * Sea Change
 * The Finale

Season Three
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 * The Awakening

Trivia

 * Cleo was the last to learn about her powers.