What Plans? said:
It would be hilarious if he was all sweet and cute around Qui-Gon, but then turned to mini-Vader around Padme. :P
I like this. Even if the Vader voice slips out just once or twice it would be pretty funny.
At one point in the movie, Obi-Wan says to Qui-Gon: "The boy is dangerous. They all sense it, why can't you?" Then right after he says that, maybe you could flash back to the one or two times in the movie where the Vader voice came out of Anakin.