Disclaimer: nothing's mine.
In the shadows :
Kirk had been alone most of his life. Bones didn't need to hear the story to understand it. Bones didn't like being there for others, because he was not good at it – his former wife was a striking example of that. He was better off alone.
Strangely enough, though, he never complained when the kid stuck around. He pretended Kirk annoyed him but he was actually glad to have him near.
Once, after Nero, after everything, when Jim was congratulated, admired and loved, Bones felt as if he were not needed anymore, and that hurt him more than he would admit. But then Kirk's nightmares came back and the sobs and the feeling of being crushed by the boy while Bones was holding him and the nevereverleavemeBonespleaseplease made him understand that he was the only one. He always would be.
And sometimes, while taking a sip of bourbon and thinking about his little girl, and feeling as if the whole world had suddenly put all of its misery on his shoulders, he was glad to feel the warmth of Kirk's body behind him. He would never tell him, but he needed Kirk probably more than the kid needed him – and somehow, Bones was pretty sure his Captain knew it.
And when Jim was showing off and being great, and when all eyes were on him, Bones, in the shadows, only felt proud, only felt his love for him, because in the end, Bones was the only one able to call Jim his.