Only a bat.

So much more she had been, so much greater, before the Lord had gone over the Sea. So fierce in her hunger, so huge in her anger. She had sailed through endless night like the Dark Lord’s rage. Such creatures had fled screaming from the ragged shadow of her wings.

Resentful, Thuringwethil tracked the intruders to the rim of a broken stone staircase descending into the deeps of the pits. Frost glittered on the first step.

She settled under a nearby ledge and folded her wings around herself. She could wait. When they emerged...

... if they emerged...