Dark
The dark brought out Ulquiorra's scarier features. He knew from the way Ulquiorra breathed that he wasn't asleep, just resting his eyes. The dark swallowed all of Ulquiorra's hair, his markings, until only his face glowed in the moonlight like a ghost. Grimmjow didn't like the way Ulquiorra looked at night in the dark, so he wondered why he stayed up to watch the fourth sleep, even though he never succeeded. He always fell asleep before Ulquiorra did.
Ulquiorra's face, so still, with no features, no eyes, no nothing, just the oval of white floating in the dark, and no matter how much he tried to see more, there was nothing. And just when he was about to panic, he didn't know why, but the lack of anything scared him, Ulquiorra's hand on his arm would grip tight, his eyes would open, emitting a light of their own.
"Go to sleep." and that would always make the dark shrink away from Ulquiorra's face, allowing Grimmjow to curl and clothes his eyes safely.
Owari