"There are. We'll have to put up barriers around the place we use in addition to the seals on him, to compensate for the lack of Darkness-proofing."

Because keeping him sealed would do little good if the monsters could just keep breaking in at night. This could evidently take up to a few days; they needed the precautions.

And yes, the kid would be fine for a bit on his own. Run-of-the-mill Darkness creatures wouldn't be able to break through that spell.

"Let's get this done, then."