**Arclight is about loss**
Everyone inside the Arclight has lost something integral; some have lost everything but their lives.
The humans, in general, have lost the world to the Fade. They've lost the beauty of a night sky, the moon and the stars. And so, they've lost their sense of direction, in a way. They no longer know how to navigate, so they're stuck.
Marina has lost her family, and her home, but worst of all, she's lost her memory of both. The trauma of enduring the Fade attack that left her an orphaned refugee cost her her past. And without the knowledge of who she was, she has no idea who she's supposed to be. She's terrified that finding the truth may tell her she's a coward who abandoned everyone she loved to a fate she couldn't face, and so it's easier for her to let the strangers who rescued her fill in the blanks at first. But that's a loss, too - a loss of her true self - and she can't tolerate it for long.
Many of the Arclight's children have lost at least one parent in the fight against the Fade. Among these is Tobin. He lost his mother as a young boy, and now has to live with the knowledge that his father chose to die protecting this girl he didn't even know, rather than returning safely to his own son.
And finally, the Arclight itself has lost its sense of security. Before Marina's rescue, the Arclight existed in a strained safety bubble. The Fade seemed to have decided to keep to their own territory, content with a state of non-aggression. After her rescue, that cease-fire suffers a violent end - because as much as the humans want to discover the secrets of Marina's survival, the Fade are similarly determined to make sure they never do.
There are no easy choices when so many have lost so much, but those choices still have to be made, and that means they will cost someone - maybe everyone - more than they have to spare.