I don't know if you feel like I do but somebody else noticed that Zoro is calmer, cooler and colder than in the begining of the series???
In the beginning I found him hot-fired not as much as Luffy or Sanji but still a bit… Sometimes he smiles or laugh with the crew and did goofy things but with the beginning of the DBF he change... He shows no emotion even if one of his friends (Chopper) are crying or like Merry dying... and have no big realationship to others of the crew. He alwasy does whta he had to do for the crew or what Luffy says him but it seems that he doesn't care much about it..
For me he is the only one how change his character...
Luffy is still... Luffy
Nami is still... Nami
and so on...
Maybe Robin will change a bit but it will be a positive change cause all of his troubles are gone with this arc.
So my question is... Wha do yout think happened that Zoro seems to be changing???
Maybe the Kitets or lost battles like against Eneru or Ao Kiji or is he just sick of goofing arounf with the others???