Working out what was Plato's and what was Socrates' is, of course, a difficult and occasionally paradoxical task. I think it is pretty clear that Plato was puzzled by Socrates, and tried various solutions to deal with Socrates' serene assumption that his method (sometimes referred to as antipeirasmic) was appropriate for the working towards the truth. These solutions changed over time, and one can see an evolution in their manner. The other sources at least give us some evidence that Socrates wasn't just a figment of Plato's imagination.

yours,

Peter