Renji always had a thing for Rukia and even now he still does even though Rukia and everyone else is oblivious, even Byakuya. Renji thought that Rukia would never accept his love and that she would fall for Ichigo or maybe even Byakuya and marry one of them, but Renji would have never thought that she would have accepted them. Rukia had to admit that when she first met Renji she thought he was a bit cute and had a little crush on him, but it was never big enough to lead to love. When it became love was when she left Renji and went with Byakuya when they were in the Academy, Rukia would never actually admit to anyone that she felt really lonely without Renji and when she saw him again that love fluttered and grew even bigger than it was before.
Renji wanted Rukia, but just too afraid to come out and tell her, if he got rejected then there friendship would become awkward and he didn't than that would be a blessing. Rukia wanted Renji as well, but was still unsure of the feelings for him even after all the trial they went through. Ichigo had saved and was big too and strong like Renji, but wasn't Renji and didn't have his personality, Byakuya was nothing like Renji, but had a charm that just attracted her.
Renji would stay up late thinking and thinking of Rukia and just to see her smiling and being by his side was enough, they were alone when each other wasn't around.
Rukia would often come to 6th squad barracks and visit Byakuya or drop of documents, and just seeing her and teasing her was enough to warm his heart and make him happy. Rukia enjoyed their arguments and fights, it made her happy that she had someone like Renji and that she ever met him. The more they waited the worser thing would become, Ichigo might confess his love or affection for Rukia and maybe Renji just might give up. Renji dwelled on those thoughts and Rukia not so much since she didn't love anyone as much as she did with Renji.
The day came though when Renji showed his feelings for Rukia and well she wasn't expecting him to be so rough with her, but the roughness just excited her.
Rukia had been finishing up some of her captains paperwork and was reading to leave for the night and have some special elder dinner that was a choice. When Rukia was leaving she met Renji who happened to be at the door of her Captains office, she smiled up at him, even though it was dark since she had turned off the lights so the only light was the moon that shined on her face and shined on his lower body and half his face. Renji just stared at her and then out the wall windows, Rukia noticed something odd about Renji when he looked to the windows. Renji walked over to where she was standing and hugged her amorously, Rukia had her arms at her side and looked to Renji who was hugging her, what's wrong, she thought.
"What's the matter Renji?"She asked and Renji felt his chest warm up, just the sound of her voice and her calling him made him even warmer. It was time that he told her of his feelings, but just didn't know how to put it in words, it was a love to strong for words themselves, he let go of Rukia and held onto her small figure. He looked into her light bluish purple big eyes that seemed to sparkle and light up and Rukia looked into his which seemed to have the same charm as Byakuya, they were a light brown color that looked strong and full with emotion. Rukia couldn't help but think that Renji's expression looked as if he was going to devour her at that moment and well her perverted thoughts were right for once. Renji kissed her with force, but was also gentle at the same time; his lips were chapped a bit but also warm, Rukia seemed to melt into the kiss. Rukia was surprised at the Renji's actions and how he seemed so full with emotion and sadness, the kiss said the whole thing and Rukia accepted it. Renji kept on kissing her and Rukia kept on returning it, Renji lye her down on the couch in the room and Rukia stared up at him.
His arms were so strong and ruff, his chest was so build and his stomach was hard, his body was in shape and large compared to Rukia's tiny self. Rukia's body nicely shaped, her skin was as smooth as a babies, her hair was incredibly soft and smooth, as well as Renji's. Renji and Rukia moved in each other and became one on this full mooned night in the 13th squad barracks.
Every since that day Rukia and Renji have kept there relationship and "activities" a secret, Renji seen it as a game and Rukia was led on by the game. They would act friendly when ever encountered or in front of their friends and captains, but when night came or sometimes in the day they would come out to play and once claim what is both there's and there's to keep.
I was really bored and Renji and Rukia just happened to be in my mind as well as Bleach of course, anyway I'm not sure if it's a one shot, but whatever.