After landing on the Punk Hazard, a dragon appears before Luffy and his nakama. And seems that the dragon can talk to them but start its attack in a moment. Fire was jetted from its mouth. This
action make Luffy and Zoro angry, both of them start their "revenge". At the help of Robin and Usossp, Zoro kill the dragon finally.
Vut when Luffy ride on the dragon's back, he found the the talker not the dragon but a human who plug on it. Seems that the man was attacked by Shichibukai so he want to fight back and control the dragon to attack Luffy, because he think that there are the pirate. Luffy drag him apart from the drago, then find that this man only have his leg withour main body. He kicked Luffy and know that he is not his definition then runaway. Seems that Luffy feel interesting in this strange guy, and follow him invite to join them. Looking at the dressing style og this leg person, he just like the warrior in the Thriller Bark: Ryoma. If you still remember this guy, you will know that he used to kill a dragon in the legend. And in his country, warrior was the leader and almost all of them are swordsman also very strong. It;s can be a attaching to Zoro.
At Thousand Sunny, Sanji, Chopper, Franky, nami and Brook was fainted due to the posion gas. But the unknown man said that their has catched two human(Sanji and Nami), a robot(Franky), a pet(Chopper), and they never mentioned Brook. It's really strange and thinking about the special relationship between Brook and some warriors, I am afraid this is a foreshadowing of Oda!