He had been here a while now and it did not seem like this was just a passing dream or merely some illusion he was seeing at the end of his life. He wasn't so desperate as to cling to life after defeat, so this place was not a part of his own imagination. It was however interesting how a place could pull him from his death and give him back his existence as an Arrancar. It was obviously sentient to some point, which was a concern.
He had no intentions of being a trapped pet, but according to the information he had gathered, it wasn't like he had much of a choice. He was stuck here, as was the other people he had met. So for now, he could only play along, wandering the halls quietly, not making any sound as he walked, drifting along gracefully in his more human form.
He stopped though, when he sensed something familiar and turned to walk over to a door that he hadn't noticed earlier. He didn't hesitate, opening the door-- and then he blinked a few times. That familiar dark sky with only the crescent moon illuminating silver sands and dead trees scattered every here and there. No doubt it was just like Hueco Mundo.
No hollows though. No Las Noches towering in the distance. "A replica, huh..."
Regardless of if it was just a replica or not, Arrancar were originally Hollows, and Hollows were originally human spirits who simply lost themselves and thus they hungered and craved familiarity, and anything that could make the emptiness go away. It was the kind of creatures they were. So, Ulquiorra took a step inside, gaze fixed on the moon and the sky. It was strange. It was one of this place's tricks, but... It seemed so very real.