And perhaps they are walking silently because the security system attacks the Others, too. It would make all the line-drawing by Zeke a little more explainable, too.

What if those kids walking are "outside their designated area"?

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charlie98210
"Whoa!" she said. "Cry 'Havoc!' And let loose the dogs of war!"
And, like Banquo's ghost, they just won't go away.