"Nami-ya here, hand me the comb" Law said.
"Huh, wha-" Nami began as she tried to turn before Law took her comb and forced her to face forward again. She was about to ask him what the hell he thought he was doing when she felt him begin to comb her hair and stopped. They ended up sitting in silence as Law began to tease the knots out of her hair.
They had just been sailing in a fierce storm and though Nami had been glad that they were safe for the time being, she had not been amused by the way her ginger hair had somehow magically knotted itself in the most complicated ways as possible. She'd sulked at the ridiculous effect the wild wind had on her hair but in the end she had realised that, well, it wasn't going to sort itself out and she might as well try her best to bring it under some resemblance of normalcy.
She could feel his long fingers gently undoing the knots out of her hair and under the even rhythm he set once he had finished straightening her hair and began to brush it, she lost herself in her thoughts. She began to reminisce about her childhood memories (the good ones of course). Nojiko used to treat her hair with the same care; she always had this way of making her hair look it's best. She knew exactly how to make her ginger hair shine and bring out the vibrant colour that was alike to the oranges in the grove.
Nami sighed happily. It was soothing to just have a few moments to herself without having to organise things on the ship (honestly Nami was more of a responsible captain than Luffy was).
And then she realised that she wasn't technically having a few moments to herself and she remembered that there was in fact someone behind her brushing her hair. It took her a few moments to realise that her hair was actually pretty normal already and that Law was just aimlessly combing he same area again and again.
She turned slightly to see him staring out at the sea. He seemed to be lost in his own thoughts so she gently shook him on the arm.
"Hey, Torao-kun, are you done yet?"
He seems to jolt back to reality then and realise where he was. He glanced down, handed the brush back, nodded a little and turned to leave.
"Hey Torao?" He stopped and twisted around, hands in the pockets of his spotted jeans, waiting for Nami to continue. "How come you're so good at combing girls hair?"
His eyes stared into hers for a few moments before he averted his gaze. "I used to comb my own sister's hair when I was younger." He looked slightly bored but when slightly awkward silence lingered and Nami was about to say something, he quickly muttered, "Your hair is a lot like hers used to be." He seemed to realise what he'd just blurted out then, blushed madly and then walked off, trying to hide his embarrassment by burying his face in between the feather collar of his shirt and the bill of his hat.
She chuckled and wondered what sort of older sibling he would have been. She was willing to bet that he was a lot like Nojiko.
Headcannon: When Law helps Nami with combing her hair and she asks how he came about to being so good at it. His experience is from combing Lamie's hair in Flevance