History YMMV / H2OJustAddWater

* UnintentionallyUnsympathetic:
** Will in "Kidnapped". He notices that Bella flees from water, so he dumps a glass of water on her when he's sure she can't easily run away from him. As a result, he discovers she's a mermaid by violating her trust and forcing it out of her. Later on in "Crime and Punishment", the gang finds out that Rikki has been kidnapped, and Will is the only one who knows where she might be, information he withholds until he confirms that Rikki and Cleo are mermaids as well. Bella still gets together with him after that, and he implies that her being a mermaid is the most attractive part about her.

** Emma in "The Big Chill". It appears as though she expected Rikki to start work immediately without giving her any kind of training on how she should behave on the job, and doesn't tolerate ''any'' mistakes. Judging by the end of the episode, where she's getting tips, it seemed Rikki's mistakes were more out of ignorance and being out of her depth. Given how Emma was against hiring her from the start, it seems as though she was hoping Rikki would fail.
** Miss Chatham in the Season 1 finale has Lewis lie to the girls that their powers would be gone forever if they got into the Moon Pool; claiming that if they believed it, Dr Denman would too. Except there was no need for the girls to be kept in the dark as well, or at least told as soon as they were home. It's [[MoralLuck just luck]] that none of the girls were seen when their powers returned - Rikki was on a public beach! Miss Chatham's lying could have resulted in the very problem she was trying to save the girls from.

** Zane in season 3, big time. He basically goes back to being a snobby, scammy, arrogant jerk, even going as far as kissing Will's "evil" sister Sophie right in front of Rikki, his GIRLFRIEND, and then declaring "it was nothing" to her when she rightfully called him out on that. Later he tries to blackmail her back into the relationship, throwing in such hints as if he doesn't need to "keep the secret anymore". And that's while still keeping Sophie close. It's like he was stripped off of his previous character development where he could be mean and pushy, but never as bad.

** Also Rikki, despite being poor, cringes at the simple idea of getting a job and barely even tries at the Juicenet Cafe, only getting Emma into trouble. Lately, she picks up something simple and illegal, instead.

** What makes this even more frustrating in the end is that while she appropriately gets punished for her actions, the group were still able to get away with how they treated her[[note]] Just as she gets away with being an abusive girlfriend, breaking and entering, theft, imprisonment of Emma and Cleo, and bullying someone to the brink of AttemptedSuicide.[[/note]]. Hell, Nate, who has done way creepier stuff and worse, at times, mostly got a slap on the wrist compared to Charlotte herself.

** Charlotte suddenly ForgotAboutHerPowers when she only learned to dry herself off quickly ''just the previous episode'', instead choosing to hop into the dolphin's tank as she transforms and getting herself into a panic.

* ContrivedCoincidence: Many many many many many many examples.

** There's also the fact that they made fun of and scolded her for a ''phobia'' she had.[[note]] Sure, she shouldn't have tried to injure Ronnie the dolphin like that, but she was still acting out of fear and poorly thought out self-defense.[[/note]] There's also some JerkassHasAPoint at play; the girls claim that dolphins are harmless, but Charlotte's claim that one was harassing her is completely realistic. Even playful behavior of dolphins can wind up harmful to humans.

** There's also the fact that they made fun of and scolded her for a ''phobia'' she had.[[note]] Sure, she shouldn't have tried to injure Ronnie the dolphin like that, but she was still acting out of fear and poorly thought out self-defense.[[/note]]

** What makes this even more frustrating in the end is that while she appropriately gets punished for her actions, the group were still able to get away with how they treated her[[note]] Just as she gets away with being an abusive girlfriend, breaking and entering, theft, and bullying someone to the brink of AttemptedSuicide.[[/note]]. Hell, Nate, who has done way creepier stuff and worse, at times, mostly got a slap on the wrist compared to Charlotte herself.

** Not only that, they've been keeping her own family history from her. Then, when she finally found out and tries to bond with the group once becoming a mermaid they still continue to villainize her.

** After all of that rude behaviour, secrecy, and antagonizing that she had to endure just so she could fit in, is it really that surprising when she snapped in the end and pulled a FaceHeelTurn in retaliation for all of that?
** What makes this even more frustrating in the end is that while she appropriately gets punished for her actions, the group were still able to get away with how they treated her. Hell, Nate, who has done way creepier stuff and worse, at times, mostly got a slap on the wrist compared to Charlotte herself.

* DesignatedVillain: Charlotte, who before going all-out evil arguably doesn't really do much wrong to the girls, even though her relationship to Lewis comes off as rather pushy from the start. Can you really blame her for getting a tad upset and suspicious when Lewis continually lies to her, or runs off or stands her up with little to no explanation to go and hang out with three other girls? To Charlotte's credit, in the beginning the show presents it more as Cleo being petty than anything else, and she does plenty of legitimately nasty things as part of a FaceHeelTurn to become a true villain. She also starts antagonizing Cleo early on, episode 6 of the season having already established a ''mutual'' dislike.

* DracoInLeatherPants: After a while some fans begin to realize how sympathetic Charlotte really is in some parts, ''especially'' considering how the main cast treats her throughout most of Season 2 before she snaps. Though, a few fans often go overboard with it, downplaying and sometimes even outright ignoring what she did in her final appearances. Even before getting together with Lewis, she shows signs of being very creepy and controlling, spying on him and meddling in his private business with the girls, as well as jumping at every opportunity to make Cleo look bad and not respecting Cleo's privacy as she repeatedly goes through her stuff. The others have every right not to want to be friends with her,[[note]]though they didn't have to be too harsh to her at the beginning of the season[[/note]] and she does several things that are recognised as symptoms of emotional abuse (including hiding Lewis' phone and trying to control who he hangs out with). Despite everything she did to Cleo, the girls still try to warn her about the full moon, and she resorts to using her powers in a way that could nearly ''kill'' them.

* DracoInLeatherPants: After a while some fans begin to realize how sympathetic Charlotte really is in some parts, ''especially'' considering how the main cast treats her throughout most of Season 2 before she snapped. Though, a few fans often go overboard with it, downplaying and sometimes even outright ignoring what she did in her final appearances. Even before getting together with Lewis, she shows signs of being very creepy and controlling, spying on him and meddling in his private business with the girls, as well as jumping at every oppprtunity to make Cleo look bad. The others have every right not to want to be friends with her,[[note]]though they didn't have to be too harsh to her at the beginning of the season[[/note]] and she does several things that are recognised as symptoms of emotional abuse (including hiding his phone and trying to control who he hangs out with). Despite everything she did to Cleo, the girls still try to warn her about the full moon, and she resorts to using her powers in a way that could nearly ''kill'' them.

** Byron, Emma's {{Adorkable}} and slightly dim love interest from Season 1, gets replaced with Ash, who's a bit of a DesignatedHero and the noticeable age difference between them makes their romance slightly off-putting (Craig Horner was five years older than Claire Holt, who was only seventeen at the time). Due to both characters being PutOnABus in Season 3, he ultimately feels like a pointless recurring love interest. This reaction to the character, may have contributed to the decision to just bring back Byron for ''WesternAnimation/H2OMermaidAdventures''.

* DesignatedVillain: Charlotte, who before going all-out evil arguably doesn't really do much wrong. Can you really blame her for getting a tad upset and suspicious when Lewis continually lies to her, or runs off or stands her up with little to no explanation to go and hang out with three other girls? To Charlotte's credit, in the beginning the show presents it more as Cleo being petty than anything else, and she does plenty of legitimately nasty things as part of a FaceHeelTurn to become a true villain. She also starts antagonizing Cleo early on, episode 6 of the season having already established a ''mutual'' dislike.

* MorePopularReplacement: The closest thing to a recurring antagonist in Season 1 was the generic AlphaBitch Miriam. She vanishes in Season 2, and that season's antagonist Charlotte is a far more memorable character; even getting to become a mermaid herself.

** Mermaid stuff aside, some of Charlotte's behaviour towards Lewis is actually disturbingly reminiscent of real life emotional abuse. She tries to control who he can see and talk to, hides his phone from him to prevent Cleo from calling, tricks him into hurting Cleo in a KickTheDog moment and ultimately lies and manipulates him.

** Not only that, they've been keeping her own family history from her. Then, when she finally founds out and tries to bond with the group once becoming a mermaid they still continue to villainize her.
** There's also the fact that they made fun of and scolded her for a ''phobia'' she had.[[note]] Sure, she shouldn't have tried to injure Ronnie the dolphin like that, but she was still acting out of fear and poorly thought out self-defense.[[/note]]

** Rikki, Emma, and Cleo sabotage a family dinner between Cleo's father and Charlotte's mother in an attempt to drive them, as well as Charlotte and Lewis, apart - never mind that at this point, Lewis was single because ''Cleo turned him down'', and therefore fair game for Charlotte, who at this point has been nothing but a decent person.

* DesignatedVillain: Charlotte, who before going all-out evil doesn't really do anything wrong. Can you really blame her for getting a tad upset and suspicious when Lewis continually lies to her, or runs off or stands her up with little to no explanation to go and hang out with three other girls? To Charlotte's credit, in the beginning the show presents it more as Cleo being petty than anything else, and she does plenty of legitimately nasty things as part of a FaceHeelTurn to become a true villain.
* DracoInLeatherPants: After a while some fans begin to realize how sympathetic Charlotte really is in some parts, ''especially'' considering how the main cast treats her throughout most of Season 2 before she snapped. Though, a few fans often go overboard with it, downplaying and sometimes even outright ignoring what she did in her final appearances. Even before getting together with Lewis, she shows signs of being very creepy and controlling, spying on him and meddling in his private business with the girls. The others have every right not to want to be friends with her,[[note]]though they didn't have to be too harsh to her at the beginning of the season[[/note]] and she does several things that are recognised as symptoms of emotional abuse (including hiding his phone and trying to control who he hangs out with). Despite everything she did to Cleo, the girls still try to warn her about the full moon, and she resorts to using her powers in a way that could nearly ''kill'' them.

* DracoInLeatherPants: After a while some fans begin to realize how sympathetic Charlotte really is in some parts, ''especially'' considering how the main cast treats her throughout most of Season 2 before she snapped. Though, a few fans often go overboard with it, downplaying and sometimes even outright ignoring what she did in her final appearances. Even before getting together with Lewis, she shows signs of being very creepy and controlling; spying on him and meddling in his private business with the girls, as well as locking Emma and Cleo in a room and trapping them in their mermaid forms because she doesn't like their opinions. The others have every right not to want to be friends with her,[[note]]though they didn't have to be too harsh to her at the beginning of the season[[/note]] and she does several things that are recognised as symptoms of emotional abuse (including hiding his phone and trying to control who he hangs out with). Despite everything she did to Cleo, the girls still try to warn her about the full moon, and she resorts to using her powers in a way that could nearly ''kill'' them.

** Dr Denman was willing to basically ''kidnap'' three girls to experiment on them, presumably never telling their families. And what was she going to do with Lewis, who would out her as soon as he could?

** In the finale of Season 1 Cleo wonders if Dr Denman is gonna see if they can talk to fish. A few years later in ''WesternAnimation/H2OMermaidAdventures'' the girls can do just that.

** Brittany Byrnes has said that, even though Charlotte ''was'' a villain, the things she was hated for were not the villainous acts like trying to strip the girls' powers but the more annoying things like micromanaging Lewis's birthday party or trying to become part of the group.

* DracoInLeatherPants: After a while some fans begin to realize how sympathetic Charlotte really is in some parts, ''especially'' considering how the main cast treats her throughout most of Season 2 before she snapped. Though, a few fans often go overboard with it, downplaying and sometimes even outright ignoring what she did in her final appearances. Even before getting together with Lewis, she shows signs of being very creepy and controlling; spying on him and meddling in his private business with the girls. The others have every right not to want to be friends with her,[[note]]though they didn't have to be too harsh to her at the beginning of the season[[/note]] and she does several things that are recognised as symptoms of emotional abuse (including hiding his phone and trying to control who he hangs out with). Despite everything she did to Cleo, the girls still try to warn her about the full moon, and she resorts to using her powers in a way that could nearly ''kill'' them.

** Ms. Chadam somehow knowing the girls are mermaids.

* AlternateCharacterInterpretation: With TheReveal in Season 2 that Rikki is [[spoiler: actually a lonely poor kid]], her dislike of Zane in Season 1 has multiple possibilities. The first is that she just thinks he's a jerk. The second is that she hates him [[spoiler: because she's jealous of what she doesn't have]]. The third is that there could be romantic feelings from the start but she's acting {{Tsundere}} because [[spoiler: she believes he'd never be interested in a poor girl]].

* LesYay: It's a series about a group of teenage girls who often seem to like each other a lot more than their boyfriends. What do you think? (Polyamorous fics are...[[RuleThirtyFour not unheard of]].)

* SeasonalRot: Season 3 is considered this to many fans as Emma, and later on Lewis, [[BackForTheFinale (until he returns in the end)]], are replaced with newer characters such as Bella and Will. While Bella is a mixed bag, Will does a ton of questionable things throughout the season that in retrospect, felt uncomforting to watch. Furthermore, other changes such as the different necklaces, the water tentacle being as a new threat instead of the Full Moon (with the latter not having any plot/conflict all season long), and possibly the [=JuiceNet=] Cafe now being called Rikki's Cafe makes the entire Season feel disconnected from the first two. Lastly, aside from Emma being mentioned, most of the past events of the first two seasons is barely discussed as well.

* SeasonalRot: Season 3 is considered this to some fans as Emma, and later on Lewis, [[BackForTheFinale (until he returns in the end)]], are replaced with newer characters such as Bella and Will. While Bella is a mixed bag, Will does a ton of questionable things throughout the season that in retrospect, felt uncomforting to watch. Furthermore, other changes such as the different necklaces, the water tentacle being as a new threat instead of the Full Moon (with the latter not having any plot/conflict all season long), and possibly the JuiceNet Cafe now being called Rikki's Cafe makes the entire Season feel disconnected from the first two. Lastly, aside from Emma being mentioned, most of the past events of the first two seasons is barely discussed as well.

* ValuesDissonance:
** Cleo working at a marine park has not aged well, taking the treatment of the animals in real life into consideration. It was most likely for this reason that she works at an oceanic center in ''WesternAnimation/H2OMermaidAdventures.''
** Dr Holt in "Under the Weather" comes across as much more reasonable now than the MadScientist she's portrayed as, especially after the UsefulNotes/COVID19Pandemic. From her perspective, the girls are displaying unusual symptoms that are wildly inconsistent with any normal illness. For all she knows, it could be a dangerous new virus that requires careful study to avoid an outbreak, and she was 100% right to have everyone in the house quarantine indefinitely.

** There's also the fact that they made fun of and scolded her for a ''phobia'' she had.[[note]] Sure, she shouldn't have tried to injure Ronnie the dolphin like that, but she was still most likely acting out of fear and a poorly acted self-defense.[[/note]]

* TheyWastedAPerfectlyGoodCharacter: Miss Chatham is {{Brother Chuck}}ed in Season 2, never getting to interact with the granddaughter of her teenage best friend or offer the girls any guidance on what to do about Charlotte.