Naruto and Sakura work out well, to everybody's surprise. It starts out simple enough. Whenever he is assigned for a mission, she'll see the whole team off at the gates, fussing like a mother hen - or rather, like the medic she is. Now, don't get yourself into any unnecessary dangers, you hear me? Listen to Kakashi, and don't let your wounds go unchecked. Even better, don't get any, okay? Make sure you're eating, and for god's sake, don't skip out on the vegetables.
Naruto will beam at her, delighted at being the centre of her attention, and answer something along the lines of, Aww, Sakura, you do care! She'll whack him over the head with an indignant huff. Ow, alright, alright! I promise I'll do everything you told me. Honestly.
She never answers, instead pulling him into a quick hug before sending them off on their ways to god knows where while she returns to her shift in the hospital. Sometimes Kakashi wishes she wouldn't insist on seeing them off, because it has Naruto skipping ahead of the group grinning like an idiot, and it's difficult to keep up with him.
Needless to say, Naruto, despite giving it his all, can't heed her commandments. Being the brash shinobi that he is, he never listens to his team leader and instead plows ahead only to plant himself in (completely avoidable) dangerous situations. He forgets checking his wounds because he is too busy caring for his comrades, never mind the Better yet, don't get any part. They are ninja, a sentiment like that is only wishful thinking and they both know it. But she fixes him up alright every time as soon as they return home, all the while scolding him for not taking better care of himself, and he beams up at her despite the harsh words because it means that she cares.
The only thing Naruto adheres to when on missions is the Eat your vegetables. No matter how much broccoli some half blind inn keeper decides to heap onto his plate, he gobbles it down in record time before moving on to the good stuff, as he calls it - stuff that would undoubtedly have Sakura keel over in all its glorious unhealthiness.
After a while, there is a shift in the way they both say their goodbyes. Sakura is still as violently determined as ever to drill the importance of taking care of himself into her blond team mate's head, but after she's rattled off her list and whacked him over the head, she pushes a nicely wrapped bento into his hands and pulls him into a hug - a different hug than before. This one is more gentle and soft, and whenever she does it Naruto closes his eyes and rests his chin on her shoulder for a moment.
And he still goads her about caring after all, but the tone of his voice has changed, and from his eyes shines the unshakeable certainty that she really and truly does. This is what Kakashi in hindsight fondly dubs 'the Bento Phase'.