Jimmy knows most people would find the hero worship thing he's got going for Ducky a little weird, but frankly, most people find most things about Jimmy a little weird. And the doctor needs someone who's capable with his hands and enjoys the little war stories and historical anecdotes, which is probably a difficult trait to come by in an assistant if Gerold's love of his iPod was any indication.
They think Jimmy's weird because he's kinky, because he's a little bit obsessed with shoes and because fetishistic tidbits about his life keep coming up. Ducky's never around when Jimmy's perversions are the topic, though, and it's just as well. Jimmy doesn't think those things are weird, really, but he does think the team would raise an eyebrow if they ever found out just what his sex life's like.
He likes kissing. He really likes kissing. He likes kissing enough that he didn't have a problem at all with Agent Lee's tendency to put her hand up her own skirt while he was kissing her, as long as she'd let him put his hands on her shoe from time to time and nuzzle the sole occasionally, dirty leather against his face. Other men get an erection from thinking about such a thing, Jimmy knows, but it doesn't bother him that he doesn't. His laundry list of half a dozen little kinks like that is enough to sustain him without sex, without all the stuff that to him just seems awkward or weird or a little uncomfortable. He's not a virgin, but there's fewer things that can make his dick go down faster than a girl using its hardness as proof that he does want to fuck her. It's really fucked up, he thinks, that someone can talk about fighting rape, not blaming the victim, out of one side of her mouth, and then go there with the other.
And so, the symbiosis between himself and Dr. Mallard has become a kind of kink of its own, though Jimmy would never kiss his boss, or suggest anything untoward, or engage in the kind of dirty talk he has with previous partners. What he will do is watch Ducky's hands over a body, soak in the doctor's knowledge, listen to Ducky dissect other people psychologically even as he tries to do the same with Ducky. He likes knowing little things about Dr. Mallard that other people don't know. He likes seeing competencies that generally go unnoticed. He's never quite sure whether Ducky notices the degree of intensity Jimmy sometimes focuses on him, whether he's politely ignoring it or just comfortable. Jimmy likes the idea that Ducky is comfortable.
It is a case of hero worship, but he'll take it. What most people understand, won't hurt them. Ducky's never minded, and somehow, it works for them.