"Both Usopp and Chopper are in total awe of his strength and "tough-guy" attitude. He also appears to have a close relationship with Chopper, seeing as the youngest crewmember runs to him when he is scared or in danger, and the swordsman is the first one to jump into action whenever Chopper falls in the water. During the Alabasta Arc, Zoro carried Chopper on a barrow or on his head when they were crossing the desert and rivers. But the strongest display of Zoro's care for Chopper was displayed in Skypiea, when he found him seriously injured from Ohm's Ordeal of Iron, and grew angry enough to the point that he fought Ohm for revenge, a concept he normally doesn't support. This is probably because Chopper seems to care a lot about Zoro as he is usually the one taking the most damage after battle so Chopper is usually the one healing him."
On Robin and Chopper,
"He shares a taste for reading with Robin who called him "Doctor-San" when she first joins the crew, which made him dance in joy. They also seem to have a genuine sense of respect for each other, possibly due to their pursuits in knowledge; ironically, he was originally rather intimidated of Robin upon finding out that she specializes in assassinations, fearing that she will one day assassinate him once his guard has been let down, but at the same time, was amused when she first displayed her Devil Fruit powers to entertain both him and Luffy, and eventually opened up to her. His fondness towards Robin is what compelled Chopper to use his Monster Point Form against Kumadori during his battle in the Judiciary Tower. In return she treats Chopper not only an equal in terms of intellect but also with a motherly nature as she got him out of the clutches of Foxy's right hand woman."
So yeah, I had quite a few laugh about Robin told Franky not to ever talk in Chopper's body again.
