I actually love the contrast between Nami and Arlong.
I have talked about Jimbei and Arlong before but I think Nami also goes well in contrast with Arlong.
Arlong and Nami both lost someone precious to Racism.
Arlong lost Fisher Tiger and Nami lost Bellemere-san
But, both of them sought different things after the death of their loved ones.
Nami sought freedom not only for herself but also her villagers whereas, Arlong sought vengeance and left his people (sun pirates) behind.
Arlong turned his hatred towards all humans however, Nami turned her hatred only for Arlong. She didn't hate other fish-men because of their race. She even showed kindness to them, even to Hachi and Jimbei who were indirectly responsible for what she went through.
I think it's really beautiful how both of them had this much difference in them and it also shows how it is a person's decision to be cruel. They do it because they can! Even if you understand the reason behind their actions, they are still responsible for their own wrong doings.
Nami didn't turn her towards Hachi, she forgave him and gave him a chance to make up for it, which he did beautifully. She didn't hate Jimbei for letting Arlong loose because she knew it was Arlong who was responsible for his actions and not Jimbei.
I really love Nami's character. She may seem kinda violent and cheeky but she's kind, sweet, forgiving, gentle at times, and most importantly a beautiful person inside out.