Because she is a demon herself, demon and elves can speak the same common language.
But if I'm wrong just correct it
I don't think it's a problem problem, more like that brother is trying to evaluate her or something? He seems to be the more calculative type to me, and this is just my theory, but if he judges fl to be the more suitable as a regent I could see him switching sides.
I don’t think the brother is on /any/ side. His annoying ass just “wants to find the truth” in everything so he stays on “okay”-ish terms with everyone to obtain info
Also possible, if he's like that then chances are high that he'll be one of the first people to discover that fl is actually a demon- which can either be very good or bad af for fl.
Yeah, someone said he’s constantly approaching MC Bc he thinks her change in attitude is odd, so he’s definitely gonna be the one to figure it out first
Wait can someone explain the common language thing? Why is it a problem that she knows the elf dude can speak it?