I also went to check out the novel when it said that around the 20 chapters... I'm kinda disappointed that the novel version was able to give Killian a bigger role than what is presented here.
The climax scene is what bummed me out the most, I wanted Killian to say that she's family! Not stupid duke rudwig! :(
Do you have a link for the novel perhaps?
https://m.webnovel.com/book/i-thought-it-was-a-common-possession_26911054906960505/chapter-3_72318996300486244
I also saw a translation on wattpad but I think it got deleted recently
It really amazes me whenever a manwha adaptation takes great source material and completely changes the story.
Thank goodness I binged the whole novel as soon as I saw that note saying the story would differ from that point on. They weren't kidding it's a completely different and much more shallow story. So bummed.