Characters / H2O: Just Add Water

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    The Mermaids 

Cleo Setori, Mermaid of Waves

Cleo Sertori (Phoebe Tonkin) is the brunette of the group and a bit awkward, but eventually becomes more outgoing. Her powers are manipulating the shape of water, including the ability to create more water out of an existing amount. She later gains the Razor Wind power.

  • Clingy Jealous Girl: In season two, Cleo breaks it off with Lewis, stating that she can't have a boyfriend. Then when Charlotte comes along, she gets jealous and angry whenever they hang out and do things, even at one point sabotaging a dinner to try and drive the two apart. Meanwhile, Charlotte's only real "crime" is trying to make advances on an apparently single guy, as Cleo insists to her that they're "just friends."
  • Cool Big Sis: She may get into arguments with Kim, but she loves her regardless.
  • The Kirk
  • Making a Splash
  • Naïve Everygirl
  • Nice Job Breaking It, Hero: Charlotte probably wouldn't have gone over the edge if Cleo hadn't been so hostile to her.
  • Shrinking Violet
  • Sibling Rivalry: With her younger sister, Kim. They share very heartwarming moments on a good day.

Emma Gilbert, Mermaid of Ice

Emma Gilbert (Claire Holt), the "leader" of the group, is a rather serious and responsible girl. She has powers to freeze water and manipulate ice, snow, and clouds. Her actress is noticeably missing from the third series; she left to film a straight-to-video prequel to The Messengers.

  • Control Freak: A pretty good example of this is when Juicenet got a new manager who started making changes around the cafe, some of which were pretty sensible (EG, removing a product from the menu that wasn't selling, and rearranging the cold room so that the fresh fruit wouldn't freeze and thus lose flavor). Rather than try to open a dialog about it and try to negotiate and compromise, Emma just tried to sabotage him to get him fired.
  • An Ice Person/Ice Magic Is Water
  • Only Sane Woman: In the main trio.
  • The Spock
  • Put on a Bus: in season 3.
  • The Smart Girl: Probably the smartest of the three mermaids. Also often "smart" as in sensible.
  • Tsundere: For Ash. She initially hated his guts for some reason, but she eventually falls for him.

Rikki Chadwick, Mermaid of Fire

Rikki Chadwick (Cariba Heine) is the "Wild Child" of the group. She is the new girl in town but not a Naïve Newcomer, because she is rebellious and confident. Her powers initially involve manipulating heat in water (i.e. boiling it), but eventually extend to control over fire and lightning.

Bella Hartley

A mermaid since the age of nine, Bella moves to Mako Island from Ireland in Season 3. Her powers are turning water into gelatine, making water harden into crystal, and to densely compact particles to make substances explode.

    Supporting Cast 

Lewis McCartney

Zane Bennett

Dr. Denham

  • Big Bad: Of Season 1.
  • Hot Scientist: Lewis lampshades that she looks more like a model than a scientist.

Louise Chatham


Miriam Kent


  • Big Bad: Of Season 2.
  • Blonde, Brunette, Redhead: The redhead to Cleo's brunette and Rikki and Emma's blondes.
  • Brought Down to Normal: Has her powers permanently stripped from her after trying to strip Cleo, Emma, and Rikki's powers.
  • Easily Forgiven: The girls seem to get over the fact that she spent almost an entire season hating their guts and trying to hurt them whenever possible rather quickly.
  • Evil Redhead: She's pleasant enough for most of the season, but after becoming a mermaid her powers apparently go to her head and she takes out her (not unjustified) frustrations against the girls quite cruelly, even trying to deliberately keep them and Lewis apart, and later, trying to strip them of their powers permanently.
  • Face–Heel Turn: Charlotte's mermaid powers apparently go straight to her head.
  • Graceful Loser: She accepts her powers are gone and gives up on trying to make Lewis her boyfriend.
  • Heel–Face Turn: Once Brought Down to Normal.
  • Unwitting Muggle Girlfriend: To Lewis. Lewis constantly lying to her or giving her evasive answers and standing her up and inevitably ending up around Cleo (who says that they're "just friends," but acts like a Clingy Jealous Girl regardless) is the reason she starts getting suspicious of him and the girls.
  • Yandere: She slowly turns into this for Lewis. Her goal for the season finale is to get rid of the girls' powers so that she'd be the only mermaid.

Will Benjamin

  • I Just Want to Be Normal: Shades of this, as we find out that he isn't so interested in being a world-class competition diver.

Sophie Benjamin

  • Big Bad: Of season three.
  • Big Sister Instinct: She pushes her brother Will to excel in diving, believing she has his bests interests at heart.
  • Clingy Jealous Girl: ...But this is what she comes off more as.
  • Evil Redhead: She wants to support herself and her brother, but her greed becomes her downfall.
  • Greed: Her fatal flaw.
  • Manipulative Bitch: She uses Zane and Rikki to get the manager position and tries to control her brother's relationship with Bella.
  • Relationship Sabotage: Her flirting with Zane eventually destroys Zane and Rikki's relationship.