One-Shot based on this gif set I found on my dash. I've always kind of pictured them together in a backstory but never read any good fanfic on it.
post/45720359907/i-think-that-esposito-would-die-for-beckett-in-a
He loves her, he's always loved her. He knew he had to let her go, had to let her be happy, but it killed him. He hated seeing them together knowing what he did to her. But every time that she gives him that smile, the one that no one else ever sees, he remembers back to that summer they had together. All those road trips they took to just look at the stars. And the week they spent at the lake by her father's cabin. Those nights that she made sure he would never forget. Those marks that she left on his back and chest that night they spent on the roof of her building. He was the one who helped her get through her mother's murder. The first day that they met at the academy, he knew she would be important, and that he couldn't let her get away.
He is the one who pulled her out from the rabbit hole, and helped her with her father. He remembers meeting her a while back in the skating rink, but she doesn't recall. He complimented her on her neon skates, and her mother had told her to go out with him. He overheard her saying something about "that Latino smile." He had always thought that they would end up together. Everything dating, marriage, kids, town house, the whole nine yards. But when he got injured, she couldn't deal with it.
She blamed herself once again and he thought that she wouldn't forgive herself. You see, he got stabbed while patrolling an alley, and it wasn't the bleeding that was dangerous, it was the fact that it was used knife. And this knife had cut through the main muscles in his bicep. She blames herself because she was supposed to take that alley, and he was going to stay in the car. But she had gotten him breakfast so he repaid her. She heard him yell, and got him to the hospital. The wound was infected, and the muscles were completely cut; it took him weeks to get back on it. But thinking back to those weeks, the only thing that motivated him was her. He wanted to be healed quicker so he could drop down on that knee and pull out that ring he has been hiding from her. While he was injured, they decided it was best to take a break for a while. But when he got back to duty, she was with an FBI agent that she had met on a little boy's kidnapping case. She never told him because he was already so hurt she "didn't want to add to it by breaking his heart." So he put that ring away for now because he didn't know how serious this would be.
Then came the writer, who obviously had wanted more than just to sleep with her. And as the years went on they had all grown close to the writer, who had become part of their little family. But after she got shot, he was the one who knew what the writer said. And he knew what the writer was hiding; he disapproved even though it was saving her.
So him, watching her fall in love with another man is hard for him to do. But Javier knows he can't hold on to Kate forever.