BSG:
Remember, though, that he already half convinced himself he was a Cylon. This is a man who does not like to be on the outside, to not have a place, have prestige. He's also probably more alone and more broken now than he's been since the show began, really. On New Caprica he may have been hated, but he was the President, he had a role. On trial, he was a pariah, but he was also center of the show, the Big Bad. Now? He's nothing.
Thrust into politics, it didn't take him long to get up on his high horse, acting - and feeling - like he knew better than Roslin. Alone with the Cylons, he was their long-awaited mystery. He was the outrageously misunderstood and ill-used political prisoner, getting ready to head off on a book tour.
Now? Yeah, he saw how ridiculous and freaky it all was. And he was acting, giving them what they wanted.
But. How wonderful if it were true, if he
were
some kind of messiah, if he did have a place and a role and could heal and be loved and respected again? [And Roslin everyone would see they were wrong wrong wrong.] And of course he knows it's not true, but it
could
be, couldn't it? Maybe just a little? And, hey, if he has some lovely ladies on the side and for all I know maybe figures a way to turn a profit and...
By the time you even get to the end of the sentence Baltar is waay ahead of you. His most credulous audience member has always been one Gaius Baltar.