Arin was more than overwhelmed to see these seven kids who had the potential to be powerhouses in the future if they could be nurtured properly. And, Arin was sure he could provide them such.
In their last discussion, Aedric had informed them that it would be very hard to reunite these Orc and Lizard kids with their original clans. And it would be even harder to integrate them in the absence of their parents and being away from their respective clans for so long and being still weak at this age.
Orc and Beastman kids start their battle practice from very early ages, for in their society might is right, and weaker ones are either cast out, or sent as cannon fodder in war, or just used for menial tasks.
These kids stayed long in captivity and thus won't be able to catch up with kids of their age in their original clans.
So, it was already decided that he would bring these kids under his wing.
And anyway, Auriya and Lumiyan would enjoy having living kids around their age.
