They absolutely BUTCHERED the H2O franchise :') All the female characters are useless beyond explanation, with constant character regression and inability to remember they have powers any time it would be useful. The main male characters is 100% a Mary Sue and it creates SO MANY PLOT HOLES. It's like the showrunners had a contractual obligation that the natural born mermaids (or any women) couldn't be even PERCEIVED as stronger than the male characters.
In one scene, the merman who JUST gained his powers somehow out smarts and out powers??? (while threating) the adult, experienced with her powers, headmaster of the school????? who... does nothing???