Sik can probably act the way he does because he notices some of the considerations that Youki gives that stem from his experience in his past life.The fact that Youki refered to Sik as his "son" speaks volumes about his relationship with the whole group. I always assumed it was more like an annoying kid brother.
Also with Sik and Sophias kids, it really felt like we were seeing a glimpse into their future together. Even the line about keeping it a secret from the kids(i know last chapter i dont care)
Sofia is good wife, always took care of Creiman so that he would not overwork too hard
It's like raising an Instant Death Flag for himCreiman being a proper worker actually scared me.