After the war between Shirohige and Navy goverment, the balence among Navy, Shichibukai and Yongo has been broken. Navy lost too many soliders even general; Shichibukai left three position blank;
and the most powerful Yongo died in this war. In order to control the Grand line, Navy have to choose the new Shichibukai as quickly as possible to threat the new pirates, and Trafalgar Law has
become the new Shichibukai.
From the wor dof Smoker's G5solider, we know that Law killed 100 pirate and dig their heart out to be the presents to goverment and then got the 'honor' of Shichibukai, and this broken the impression of Law in my heart. He used to be a nice captain just like Luffy, and even saved Luffy and Jinbe in the war. I think he own the positive attitude with captain Kiddo and have the same dream with Luffy: want to be the Pirate king! I am afraid that he have some definition to do this, because after got this 'honor' can provide some convinute to him, just like in this Punk Hazarda and most of the Navy will never bother him in the New World, in my opinion.
When landing on the island, it's the destiny of Smoker, Luffy and Law, it cannot avoid will have an conflict among them. nd this is a good chance to show us the growing up of this guys.