I think some people got too worked up about this plot, is their new step sibling status weird? Yes it is. Did it get weirder by the their shared sibling? Yes it did. But still they weren't raised as siblings at all, Sohm liked Geon for such a long time and they didn't even lived together for long. Geon even took the decision to not continue with their family life. It's seriously creepy to see how much some readers want the parents to die so badly ╥﹏╥

For some reason I don't like how it goes, not that I hate this story or something, it's amazing but I readed so many comments and I feel such a negative vibe