Justin let me hug you boi! You deserves to be happy and have a good life. I know you love your sister but there's still a line between doing the right thing and the wrong one.
I totally understand them I mean who would not feel so at lost after hearing those words considering that they just kids for now even if their mentality is way beyond their physical age. They have this feeling that they can only rely on themselves in that world of course without prior knowledge...
That's creepy why would a 10 yrs old boy smile so sinister like that.
Also.. Quick Alluka your brother just switch job being an hunter and enter this world hahahah
Please remove delete or don't think about romance between brothers and sister. That was the least thing that I want to happen, I rather that she look for some love interest than fall in love with her brother.