So let me guess, the red head "sirens" Are actually true mermaid who were also the original mermaid royals and the blonde haired "mermaid royals" Are actually the "sirens". The said psycho ruler probably killed and spread rumour that he and his kins were mermaids and the true red haired royals are sirens to achieve the rule or a certain power which only a true mermaid royal can have but OBVIOUSLY he couldn't get it despite dethroning the true royals and now he's on a freak show to kill the mcs because of some stupid prophecy written.
So let me guess, the red head "sirens" Are actually true mermaid who were also the original mermaid royals and the blonde haired "mermaid royals" Are actually the "sirens". The said psycho ruler probably killed and spread rumour that he and his kins were mermaids and the true red haired royals are sirens to achieve the rule or a certain power which only a true mermaid royal can have but OBVIOUSLY he couldn't get it despite dethroning the true royals and now he's on a freak show to kill the mcs because of some stupid prophecy written.