Disclaimer: Don't own 'em. Never have, never will. Didn't make any money off of this either. It's purely fan made for other fans to enjoy freely. Thanks.
It had started around the time that they were born, so to speak, and quickly became a daily routine. It wasn't always daily; when the world crashed down around them for the first time, and the second, the encounters were much further apart. A month in time even. That lasted for only a few months, before it became every other week, and soon every other day. Of course now it was daily, if not multiple times a day.
It was so common now, that no one flinched when he stalked around, white outfit -- uniform, his mind often reminded him in a snappy manner -- dotted and splashed with dirt and blood, some of it his own but most was property of the poor unfortunate soul that crossed his path that day.
No one was shocked to see him carrying a head or maybe an arm once in awhile.
Though out of everyone, the weaker ones, the younger ones, even the higher ups -- the other Espada -- only one other was as used to this as he himself.
Ulquiorra never even batted an eye when the lower ranked Espada paraded around in a bloody uniform, not even when said Arrancar would burst into his room, completely uninvited. This happened all the time. And not once did he ever reject it. If anything he welcomed it when the feline-esque Arrancar all but manhandled him towards a wall with force that would of shattered his spine had he not been higher ranking. He didn't complain, no matter how many times Grimmjow managed to pierce his skin with his fangs; biting into his neck over and over again and staining the stronger Arrancar's collar with his own blood. No matter how much he still couldn't get over seeing his own blood painted to the teal haired male's lips and cheeks, dripping down his throat with abandon, he allowed the other to do this; to abuse him so violently.
He allowed this to happen, simply because he knew the other's secret. The real reason why the Sexta Espada loved fighting and killing so much.
Ulquiorra pitched into the game, aiding the other when he was obviously too worked up to do things properly. Stains were one thing, but rips were another. He didn't like having his uniform ripped to shreds by fangs and claws when Grimmjow got annoyed with it, so instead he'd calmly remove his own coat and place it aside. It was all like a script from then on. Grimmjow rarely changed his routine in this case; it's the only thing he stays persistent with other than killing his opponent in battle. Ulquiorra always quietly compliments him on his fervor, and Grimmjow knows when he's being praised simply because higher ranking Espada always laces his fingers through his hair, and digs his black nails into his scalp in a similar way of that of a person petting a cat.
He's never admitted it to the Sexta, but he adores it when he bites around the hole at the base of his throat, teasing the blackness with a tongue that had a softened version of the texture of that of a cat. He simply shows a minor amount of enjoyment by arching from the wall, into the teeth and tongue as silent encouragement to do more.
It isn't long before he finds himself a bit higher on the wall, feet barely touching the floor at all, as the bloody Arrancar holds him up by his arms stretched tightly above his head. He always looses the rest of his uniform as the other Espada all but rips his hakama off in one go. And it isn't long before he can watch the other's join in a puddle on the floor.
Everything from then on is a mixture of heat and white light, and occasionally someone's control slipping enough to send a hole in the wall thanks to a misplaced Cero. Afterwards the Sexta often retreats to Ulquiorra's bed, no matter how many times the higher ranking Espada has told him to leave after he's done. Personally, Ulquiorra doesn't mind it when the other curls up on his bed, hiding under the sheets now that the blood lusting pantera in him has calmed and is sated.
And personally, he'd have to kill anyone else Grimmjow would ever think of going to in order to feed that hungry cat inside. Because, even if he acts like he hates the Sexta, he loves seeing him reduced to a sleeping kitten on his bed. Because it's his job to take care of the cat; always has, and he'd be damned if he gave up what little excitement in his life that he had.