Among the Hidden
How we cite our quotes:
"Matt and me, we've never told anyone about you," Mark said, suddenly serious, which was strange for him. "And you know Mother and Dad don't say anything. You're good at hiding. So you're safe, you know?" (3.20)
If you have siblings, you know how this works: your brothers can tease you mercilessly, but the minute someone else does, they've got your back. Mark takes a break from teasing his little brother to reassure him that everything will be all right. Exactly what a big brother should do.
He might as well just rot up here in the attic. He'd thought about that before, on the rare occasions when Mother, Dad, Matthew and Mark all went somewhere and left him behind--what if something happened to them and they never came back? Would someone find him years from now, abandoned and dead? (3.35)
Check this out: Luke initially feared that he would get left behind by his family and then later on he ends up getting a fake I.D. and leaving them. Maybe it's not as scary when you're in control of the decision, but at this moment, Luke sees his family as his first line of defense. Losing that protection is just as scary as losing the woods.
Luke studied her face, seeing lines of fatigue that hadn't been there before, noticing that the hair around her face now held as much gray as brown. [...]
Luke sat up. "That's okay, Mother. I'm getting too old for this any"--he swallowed a lump in his throat--"anyway. I bet you weren't still tucking Matthew or Mark in when they were twelve." (7.21-25)
To be fair, Matthew and Mark probably weren't stuck hiding in the attic all day when they were twelve, either. But this is big step: Luke is starting to focus on his family as a whole rather than his individual needs.