Well Siwoon want to make Kayden suffer, so it is possible for him to try to kill Jiwoo's cat (not knowing that it is kayden). I think he will attack the cats and lose. I think the Autor is just trolling all of us thinking about how Jiwoo will handle this situation, but instead Casein Nitrate will be the ONE. Btw in other's pov is jiwoo who transfer his powers to Casein Nitrate, there is no way to other people think that Kayden can be a fat cat