@Mephis_to
Well as far as what's about to happen I'll put it in spoilers. Though I'll say first that technically Cecyl is full grown, the girl isn't getting any bigger, that's just what a full grown demon looks like.
The spirit link isn't sex, it's technically a spiritual/magical engagement ceremony. Basically it's just circulating magical energy between the two so that you can draw out your soul, and then it's an oath to always be together, in this and all other lifetimes. Of course most of that is already what he does with his cheat skill anyway, it just takes longer because he has to draw out Cecyl's soul. The full spirit betrothal can only happen after the spirit link has been in place for some length of time.
@BoredTears
Oh I see, Thank you for your spoil/details. I actually thought it'd also be something like this.
'Cause if it was sex then this manga would have failed itself ; to use sex as something that is serious is not in it's genre.
What's up with maids in manga talking down to their employer or other nobles. Like bitch even if the girl isn't your boss she still has a higher social position then you and yet that type of maid will lecture on proper procedure and how a noble should act then turn around and act above their own position in life.
@Morsealworth @Oberon_
Yeah other than some points mentioned, she is working for the father, not her. It seems she is seen as more of disposable Item to ensure they can maintain strength thanks to the past family deal.
Not a person that need to learn much of anything, so.
Edit - tl;dr, maybe because she is seen as a 'disposable item'
Just thought of something stupid, but I wonder if anyone's made a joke in one of these million isekai stories where one of the native characters is like "You're from another world? So you entered our country illegally."