Mark Ruffalo has admitted to being a miserable bastard on the first day on The Avengers. The star who plays Hulk said “The first day I was a miserable bastard,I was like, ‘Where's my costume man? This sucks!’ [The other Avengers] all looked dope and ripped up, and I'm there in a not very flattering linen suit. I’m the only actor to ever play Banner and the Hulk,” Ruffalo said. “So I've been working a lot with [visual effect team Industrial Light and Magic] on him.
And as for inspiration on Ruffalo’s Hulk, out went Norton’s version, as did the Eric Bana one. Instead, Ruffalo looked to Bill Bixby (70’s / 80’s Hulk)for inspiration stating ““[Bixby’s Hulk] had kind of a charm about him. He was on the run, but he was still able to flirt and smile sometimes, and occasionally he'd crack a joke.”
Finally Ruffalo also spoke about his other Avengers counterparts, in particular, one Tony Stark ““There’s a simpatico between us,” he said. “[Banner] looks at Stark and he's like, that's the dude who did what I was intending to do. He's the model. He made it work. So Banner and Stark have a very cool relationship in the movie.”
Via Marvel