A/N: My second ByaRuki fanfic. I know how unpopular this pair is because people pin their relationship as 'incest', which is technically wrong. When you realize that they are NOT related by blood then you will come know how hot they look together. And your excuse that it's "gross anyway" does not make any sense at all, so don't play that card. My rant's done...sorry for that.

But if it'll make you guys happy, these two do not have the exact same relationship as they have in Bleach, read on if you don't get it.

Something you should know: This is AU(Alternate Universe) set in the present, I totally have no idea where this story will go but it will basically follow its title, which is 'obsession'. Byakuya is a badass in this story and let me clear this right now that since Hisana does not exist, the relationship that Byakuya and Rukia had in Soul Society will not be applied in this story. You can say that I'm only borrowing characters from Bleach. Thanks Kubo^^

Note: So, I've changed this chapter, it goes in a completely different direction. I'd appreciate it if you would read this again if you had already read the previous version.

Anyway, let the obsession begin!

Heat 1

Byakuya lazily drummed his fingers on his briefcase beside him, looking outside his window at nothing special in particular.

He let out an audible sigh as he stretched out his legs in front of him. The car steadily drove on, its gentle movements lulling him to sleep. Cool air blasted on his face from the AC vents and slow, soft music played inside the limousine. Byakuya could feel his eyes droop as he tried to suppress a yawn, unsuccessfully.

Today had been an extremely tiring day at the Kuchiki Corporation. Even though Byakuya was not one to show any form of weakness, he desperately itched to get some sleep. He felt like he would have dropped dead if he had to endure another hour of grueling work.

The numerous mind-numbing meetings he had to attend and places he had to go, all in the name of his corporation's progress, were playing a toll on him. Byakuya eased back into his seat, resting his head backwards. The cool leather felt good against his skin.

Still looking out as the limo passed another street, he looked at a billboard displaying a new spring mattress. It had a semi-naked woman lying on top of it, dressed in lace and silk, her black hair splayed all around her. Byakuya mentally groaned. He could definitely think of a certain someone who he'd like to share his bed with.

The car turned left into another street and suddenly something caught his eye.

Speak of the devil, he thought.

"Renji, slow down for a second," Byakuya commanded towards the front of the limo. "Understood, sir," he heard Renji reply and the car slowed down to a snail's pace.

He looked back at the couple sitting outside the ice-cream parlor; laughing while they fed each other their desserts. Byakuya's features set into a grim line, his jaw clenching.

Rukia looked beautiful as usual; she always looked lovely. Even if she wore something as plain as a sweat shirt and pants, she would always look stunning. Right now, she was looking a bit too sexy for his liking; dressed in a miniskirt and halter top. The skirt was too short and the shirt revealed too much skin.

Not that he was a conservative by nature; he, in fact, loved what she was wearing.

It was simply the fact that she was dressed that way for someone else besides him. He knew that Rukia had to date, but did she have to dress up so much…or dress down in this case. And Byakuya knew that the boy with her was her date.

Ever since school had started, Rukia had been on three dates with three random boys from her school, and it was only the first week. To say she was popular would be an understatement. He sometimes wondered how she could manage both dating so frequently and staying on top of her class and blamed it on the lack of curriculum. He couldn't even use the excuse of failing at studies to ground her from dating. If only the school board increased the course to an unbearable level then maybe she would be unable to date so much.

Or even better, maybe she won't be able to date, period.

Byakuya had sent an application to the college on the matter but doubted they would ever consider it. Lazy sticklers.

He didn't mind Rukia dating so much as long as she behaved herself, but he still had to look out for her, he had to protect her from her dates who obviously did not think of fucking her when they looked at her long legs.

So he made sure that she only got to date any boy once, without Rukia knowing of course. He knew that wasn't the right way to go about things, preferring her to date random boys instead of one steady one, but he just didn't like the idea of another male becoming a permanent fixture in her life. Besides him that is. Call him a possessive bastard but that was just how he was.

Byakuya inwardly cringed when the two suddenly kissed. It always pissed him off to no end when he saw her kiss someone else. Again he restrained himself from going out there and beating the shit out of that boy.

And they weren't even kissing lightly; Byakuya could not help but notice. They were literally having their personal tongue battle. He could understand the boy's need to kiss Rukia, but did she have to kiss him back like she was obsessed with his lips? And on the first date? They were enjoying it a bit too much.

He'll have to go soon.

Byakuya looked closely at the disgusting boy and suddenly narrowed his eyes upon recognizing him.

"Son of a bitch."

Knock Knock

Rukia called out from her bathroom ," nii-sama, can you get that? It's probably Mathew. Tell him to wait please."

Byakuya padded lightly towards the door of his apartment. He opened the door to find a boy standing there; he believed Rukia said his name was Michael, or Mandark. Byakuya couldn't care less. He would be gone soon anyway.

"Hi, I'm Mat-"

"I don't really care who you are," Byakuya cut in, lazily looking down at the boy.

He was noticeably shorter than Byakuya. He seriously couldn't understand what the boy's attraction was; he looked pretty ordinary to him. Not the type to treat his date at a pricey restaurant. Maybe his ordinary character was the only thing going for him. But Byakuya guessed he probably couldn't afford anything decent.

That made things easier for him.

Byakuya leaned against the door frame and gave him the iciest stare. "You can only go on one date with Rukia," he stated in his trademark monotone voice, only slightly tinged with warning.

The boy looked confused, "huh?"

Rukia called out from inside the apartment, "nii-sama, did you tell Mathew to wait?"

So the 'nobody' was called Mathew? Byakuya turned around to answer, "Yes, we are just having a friendly conversation outside."

He then slightly closed the door and looked back at the confused boy, taking his wallet out from the back pocket of his pants. Byakuya took out two hundred dollars and handed it to him. The boy's confusion only grew at seeing the notes but Byakuya could easily detect the greedy way he was looking at them.

That only disgusted him more. He felt glad he would not have to stand the sight of him again.

"What's th-"

Byakuya interrupted again and lazily said, "as I was saying, you can only go on one date with Rukia, and after that you will have nothing to do with her." Byakuya narrowed his eyes, "are we clear?"

The boy quickly pocketed the cash and nodded, "absolutely."

"Smart choice." Byakuya turned around to go inside but stopped midway to look back at him.

"And you will not utter a word to her about this," he silently added before going back inside without giving him a second glance.

Byakuya clenched his fist tightly, his exhaustion quickly evaporating to give way to blind fury.

"Back to the apartment Renji," he ordered, his sharp voice piercing through the soft music like a sword.

He was going to pay Mathew a visit.

WHAM!!

Byakuya's fist smashed straight into the boy's face, connecting solidly with his nose.

"FUCK!" Mathew cried out, flailing his arms about him as he fell backwards and hit his back loudly on the wall behind him.

Blood spurted out from his nostrils, seeping into his already blood-soaked clothes. Mathew awkwardly covered his nose with his hands and tried to get up, failing horribly.

Byakuya sighed. He adjusted the brass knuckles in his fingers.

"Mathew, Mathew, Mathew," he said calmly, reaching for the front of his shirt and agilely lifting him up, setting him against the wall.

Mathew looked up at him fearfully. Byakuya just looked back at him with distaste, his slate grey eyes looking even colder.

Byakuya punched him hard, "I fucking hate it-"

Punch

"-When people-"

Punch. Crack

"-Try to screw-"

Punch

"-Me-"

Punch. Splat

"OFF!" He suddenly lifted him off the ground and easily threw him sideways, smashing him into a wooden desk. Mathew let out a blood-muffled scream as he fell on top of the desk, breaking it under his weight. The desk snapped with a loud 'crack'.

Mathew lay on top of the broken wood; his body twisted awkwardly, his breathing ragged and uneven.

Byakuya casually leaned against the wall, calmly examining his knuckles as he said, "you know, I thought you were a smart kid, but you clearly proved me wrong. "

He sighed before continuing.

"I told you in plain English that you could only date Rukia once, and you choose to ignore my warning, which was a pretty shit-assed move on your part. Fuck, whatever," Byakuya stood up straight and looked down at the bleeding boy who barely looked alive.

Byakuya smirked slightly at the bloody mess. "But tell you what; since I'm in such a good mood I'll let you off the hook." He headed for the door and tapped it twice. He then turned his head to look at him.

"Oh, and Rukia will not know about this," he commanded coolly, doubting the boy could hear him right now in his unconscious state. Renji unlocked the door and let Byakuya out, taking the blood-smeared knuckles from him and wrapping them up in tissue.

The redhead looked at the mess in the room; the broken shelves, the bent chair, the broken table and finally the bleeding boy. He whistled loudly.

"What the fuck did he do to deserve that?"

Byakuya stopped to look back at his handiwork again, considering what he should say.

"He backed up on a deal," he stated calmly.

"Is he dead?"

"No, he's alive enough to regret what he's done. Get him out of my building," he said in an emotionless tone, already looking bored with it all. He turned to walk away. Renji looked at his boss' receding back and then turned to look at the unconscious boy again.

"Stupid kid."

Byakuya dragged himself out of the lift on his floor where his apartment was, suppressing another yawn. He needed a bed now, it could be made of nails for all he cared. Right now, even that seemed very appealing. He walked towards the only door on his floor.

Actually the whole floor was his apartment. He and Rukia both lived together in his large penthouse, mainly because his company building and her college were situated near from there. Besides, Rukia was an intern at his company, so the whole situation was convenient.

But more importantly, it allowed Byakuya to keep Rukia near him 24 hours a day, 7 days a week. That was the only thing that felt convenient for him. Seeing her face after god knows how many hours was the only thing that kept him sane through the day. There clearly was a god out there.

Byakuya loosened his tie around his neck and unlocked the door. He entered and shut the door quietly behind him.

"Rukia, I am back," he called out, shrugging off his coat and shoes and silently padding his way towards the large, fully equipped kitchen.

Everything in it was stainless steel and black, all tastefully arranged by the interior designer he had hired. In fact, the whole apartment was the same, every inch of it exuded class and sophistication.

He opened the refrigerator to check its contents when he heard Rukia's door open and close, her footsteps sounding against the wooden floor as she walked through the corridor leading to the kitchen.

"Nii-sama," she quietly asked as she walked in, her features twisted in a frown as she looked at her mobile phone.

"…?" Byakuya quietly looked at her, mentally resisting the urge to kiss her for the thousandth time. Her pouting her lips was not making it easy for him though.

"Have you heard from Mathew?" She asked, looking up at him.

Byakuya deftly looked away from her lips and feigned nonchalance. "Who?"

"The boy who came on Wednesday to pick me up," she explained, still frowning as she looked at the screen of her mobile again.

"He was supposed to pick me up three hours ago but he still hasn't come. And the number keeps directing me to voicemail."

"You were going on another date with him?" he silently asked, his tone becoming icy. Rukia's head shot back up to look at him.

"Oh no, not a date. I-I was supposed to meet a couple of friends at the cinema and I...needed a ride, s-so Mathew offered."

Bullshit. Byakuya could always tell when she lied, who wouldn't. If her voice did not give it away then her expressive eyes definitely did.

So the bastard was going to go on another date with her? He secretly felt satisfied that he got to beat the shit out of him, though he should have broken a few more bones.

"Wonder why he didn't come," Rukia mused, quickly looking away from his piercing gaze.

"Hmm," Byakuya murmured, completely uninterested in the conversation. He walked around the counter towards her, wrapping his arms around her to hug her from the back. She instinctively raised her hands to hold his wrists, resting her head on his chest.

Rukia looked up at him, the worry still evident in her eyes. "I guess he's okay, right?"

His mouth set in to a grim line as he looked at her. He wondered again whether he should tell her everything. He decided against it and hugged her tighter, bending his head to kiss her lightly on her neck, right above her pulse-point.

"Of course, Rukia," he whispered in her ear. She shivered slightly but didn't move away from him.

"Want some ice-cream?" he asked offhandedly, kissing just above her collarbone again. He already knew what her reaction to that question would be.

"Oh yes yes!" she happily said, perking up immediately. Byakuya smiled at her enthusiasm for desserts. "I really want to try their new flavor, chocolate, um, something."

"Chocolate-um-something. Is that what it is called?" he asked curiously.

"Of course not, nii-sama. But it's chocolate, that's all I need to know." She tried to move but his arms were still around her. "Uh, nii-sama?"

He looked at her intently. Their faces were only inches apart. "You know what the price is," he said softly. Rukia rolled her eyes, inching forward to kiss him on his cheek.

"There, now can we go?"

He let go with a sigh. Again she chose the cheek. He was getting extremely tired of this brotherly facade. Maybe telling her the truth might not be so bad. At least it would be better than this pretense of being family.

He had grown up knowing the truth, but Rukia had been kept in the darkness. He wondered how she would handle it if he told her.

Rukia immediately grabbed one of his wrists and pulled him towards the door, giving him his coat while she pulled hers down from the rack. Byakuya helped her into her coat before putting his own on. They headed out towards to elevator.

Having ice-cream together had been their thing since long ago, it had become a ritual of sorts over the many years. The fact that Rukia considered it more important than some what's his name made him sickeningly happy. He was never going to let anyone get as close to Rukia as he was, he would make sure of it.

"Do you think I should call Mathew again?" Rukia asked in the elevator. Byakuya clenched his teeth, closing his eyes for a minute. He resisted the urge to massage his temples. That fucking name was giving him a headache.

He opened his eyes to look at her. "How about we make a deal, I will treat you to that chocolate something ice-cream, if you stop mentioning Mathew right now." His features twisted when he said 'Mathew', throwing in as much venom he could into his voice. He hoped Rukia hadn't noticed that.

She smiled apologetically. "Deal."

A/N: There you go, the chapter is different from the previous version, those who read the first one, hoped you liked this one better. I want this story to become more dark, so this version suits it more. How's the chapter titles? I got the idea from Desire Climax, a manga (not much of a good read if you ask me)