LOOKING FOR THE SOCRATES OF THE APOLOGY
Plato's Apology depicts Socrates' defense speech when he is on trial for his life. Its Socrates recounts the life that led to the charge against him. So the Apology is a natural starting point for formulating my hypothesis that the Socrates of Plato's dialogues that depict other times in Socrates' life is the same.
I do not first take my hypothesis as a datum and then try to understand the other dialogues to fit with it. My study of the Apology will sharpen my hypothesis by giving me a Socrates to look for in the other dialogues. I do not assume that I will find him. If my hypothesis is correct, my study of some other dialogues in which Socrates appears should confirm the hypothesis.
I do not take up the interesting question whether Plato intended the speech he wrote to correspond closely to what the historical Socrates said at his actual trial. Of course no one expects the depicted speech to be word-for-word the same as the actual speech. Even a team of note-takers, for which we have no evidence, would not have ensured total accuracy. At best, we'd expect only the outline and main content in Plato's Apology to be the same as the actual speech.
I mention, however, as relevant to that question a possibly revealing pun. Socrates says early on:
It would not be becoming, men, for someone of my age to come before you fabricating (plattonti) speeches (logous) like a youth. […]