Nami didn't know what to think of this pirate that kept dropping in from time to time.
She recognized him from that passenger ship the Alvida pirates raided, he'd almost landed right on top of her boat and sank her! She'd ignored all the commotion going on while she was making her escape, but she had paid enough attention to know that all the Alvida pirates had been defeated, along with Alvida herself.
Then in Shells Town... when she was sneaking around the Marine base, she'd caught a glimpse of him running around, and then later in the courtyard with a swordsman, a wimpy looking kid, and surrounded by the Marines of this base. She'd seen him again when she stopped by a restaurant to get something to eat. She'd watched in horrified fascination as he ate... it was really quiet disgusting, but she couldn't seem to bring herself to look away.
She left first, so she didn't know what happened to the wimp, but he wasn't with them when Luffy literally fell from the sky and became part of her scheme to escape the three Buggy pirates chasing her, and then Zoro turned up to free his captain from the cage.
Knowing he was a pirate, she didn't feel an ounce of remorse for setting him up like that.
But then she hung around the two of them for a bit.
He and Zoro communicated an entire plan with barely a glance, even though they had just met earlier that week and hadn't had a chance to fight together or really get to know each other.
Zoro, a man considered by many to be a demon devoid of emotion or compassion, carried the cage Luffy was in without even a thought, even though he was so badly injured and he could barely lift it.
He was a pirate, and yet... he did everything he could to help a dog to protect it's home, it's treasure. For no other reason than he could.
He went after Buggy purely for the reason that the old mayor was determined to fight him, and the old mayor would die if he did.
And then, and this one really made her mad, he left behind half the treasure so the townspeople could rebuild!
What pirate would leave behind treasure?!
In fact, the only thing remotely pirating that Luffy had done was beat on the dog a bit, but he had a valid reason for being angry seeing as how the dog ate the key to the cage.
And to get so angry over a rip in his hat!
She didn't think she would ever understand this guy... that feeling was amplified when he came after her, even after she stole his ship and took off back towards her home islands... when he refused to leave until she asked for help, and then beat Arlong simply because he made her cry. He destroyed her room in Arlong Park, her prison, for no other reason than he saw blood on her pen.
He was the most selfless person she'd ever met... but at the same time he was the most selfish person to ever sail the seas. He would protect those he cared for with everything he had, but would walk away from a stranger with no problem at all.
If he wanted you to come with him, he would not leave until he got you with him.
He was a black-hole that would eat anything and everything in sight, but one word from Sanji about low food stores, and he would be the first to start getting smaller portions, even putting some of his food on their plates, instead of stealing from them, when he thought they weren't paying attention.
He was full of nothing but contradictions.
She didn't think she would ever really understand him or be able to predict his next move.
But then... she didn't think she really wanted to.
He was Luffy, after all, and Luffy would always be Luffy.