Force.

The air was saturated with spirit particles. It practically begged them to get stronger- to relish in their strength and to enjoy it. The weak could hide and the strong could get stronger. It was a driving force in their world.

It was almost as powerful as the edgy lust that each of them carried on the back of their tongues. It was nearly painful- and many learned to tame it. He sated his lust, his tongue even bearing a symbol of the lust he felt.

But the biggest force for him was not the dull lust he felt. It was not the saturated air nor was it Aizen.

The driving force behind any hollow was simply the biggest goal for them. For some it was salvation, in Aizen. For others it was the power, in being a Vasto Lorde. For Nnoitra Jiruga the biggest goal was to finally grasp the dainty white gloves of a woman who denied him- simply to reveal the bloodstains she hid beneath the sleeves of her shirt.

His goal was to relish in her likeness to him.

That was his driving force.