**Arclight is about family**
How do you define a family unit?
Is it simply the biological connection between those who share genetic material? Or is there a wider definition?
Out of necessity, those who live inside the Arclight have become a very tight community. There's not enough people in a given section for them to be strangers with each other, and they're trained to recognize that the loss of one is a devastating blow to all. And when surviving childhood with both parents still living becomes a rarity, ideas of what makes someone family have to adapt.
Brothers and sisters are no longer only those born to the same mother or father, but also those who share experiences. They're comrades in arms, joined by a common struggle and the will to survive. Mothers and fathers aren't confined to those who give birth to a child - caring for the young becomes a community responsibility. A friend's biological mother can assimilate those without their own mother into her family. A teacher can guide his students outside the classroom. A doctor can heal more than the ailments of the body.
It's ALL one big family. Older children and teens protect the younger ones because the little ones don't always understand what danger means, or that monsters can be real. Adults protect the teens and children because it's the only any of them will live to be adults, themselves. And since this is a family, they can be a bit dysfunctional at times, but regardless of how things work out, most everyone is working together to make life better for the group as a whole.