Can someone please explain to me the siblings thing?? Is there another couple?

What "siblings thing" are you talking about?

are you perhaps talking about the twins from pearl boy?

Yes, those twins! But I can’t seem to remember them from Pearl boy at all and what role they played in the story.

Is that the brothers (who were sleeping together O.o) who worked for the villain? If so, one of them got kidnapped and brutally tortured by Dooshik and his men (as retribution for doing the same to Jooha), and the other ended up helping expose the villain in exchange for his brother's life; I think he even fished Dooshik and Jooha out of the ocean at the end.

Ahhh okay! Thank you so much. In that case I do hope the author leaves their story alone though and does not adapt it further if that’s the case (⊙…⊙ )

oh yes me too, they were really weird I feel like there is no need to continue their story at all (〜￣△￣)〜