This is Neo writing another blog that is based on an old blog, due to recent story development and simply because I can! This time I'm bringing you a slightly more in-depth version of User blog:Neowitch/Paranoid Similarities.
There is nothing quite as profitable for a creative mind as recycling one's own ideas. And it seems that Oda likes doing this a lot.
Zoro and Chopper
The first member Luffy recruited was Zoro, a guy who wanted to become the best swordsman there is, in order to fulfill the dream of the person he looked up to. For that he trained like a madman.
The first (permanent) member recruited on the Grand Line was Chopper, who essentially did the same thing: He studied like crazy to become a doctor who can cure any illness. Basically he lives Hiluluk's dream just like Zoro Kuina's.
In both arcs the main antagonist was a tyrant sort of character, abusing his high position.
In everything else though, Zoro and Chopper are absolutely opposite.
Nami and Robin
Both women were the second characters to join in their respective seas (East Blue and Grand Line). They both joined because they saw a benefit in it rather than wanting to be friends with the others and they both betrayed the crew two (canon) arcs later, just to get betrayed by the guy they made a deal with and eventually begged to be saved by the rest of the crew.
Usopp and Franky
The two engineers of the crew joined as the third member in their sea respectively. In both introduction stories the Straw Hats were in need of a new ship.
Sanji and Brook
Our two perv gentlemen share an interesting character trait as well, other than being gentlepervs and the 4th to join: After all the fighting was over they still refused to join the crew because they felt obligated to fulfill what they saw as their duty. Sanji wanted to work off his debt towards Zeff and Brook wanted to return to Laboon.
Also, both introduction arcs took place on a big ship. (And in both arcs Zoro got to fight a badass swordsman.)
Lougetown and Sabaody
Well, obviously they are the "preparation arcs". And they both introduced mighty Marine/WG-related characters whom the Straw Hats could not overcome at first.
Rivers Mountain and Fishman Island
As said before, the SH used some crazy ass current to overcome the Red Line and there were whales on the other side.
Punk Hazard and Whiskey Peak
Last but not least, when the Straw Hats arrived at their first island in the new sea they got involved with the shady business of some Mafia like organisation led by a Shichibukai using some sort of alias to hide his own involvement.
Phew, I could list some other things but it's past 2am so I'll just end here. Feel free to add to the blog once again when something comes to your mind.^^