I imagine that Yana would’ve been as opposed to changing back to his true self as John Smith was, if he’d known.
It is an interesting idea, but I think that part of what made John Smith so adamantly against re-becoming a time lord was the dichotomous nature of the Doctor himself. He is both a helper and a destroyer, a friend and a foe.
Honestly, I believe that as the Master lacks any such schism, Yana would not have had any such compunctions.
Interesting, but I would argue against that since I don’t believe that the Master is quite so black and white. While the “schism” to which you’re referring is far larger for the Doctor, I’ve never considered the Master to be out-and-out bad, just like the Doctor isn’t out-and-out good — I don’t think that his persona as Yana could have been created if it was. As I understand it, the Chameleon Arch simply provides new memories and changes their biology. If John Smith is part of who the Doctor is, then Yana is, in turn, part of the Master. And what do we know about Yana? That he dedicated his time to helping the remaining humans escape to Utopia.
Of course, it could be argued that his experience as a human in the company of other humans caused his personality to soften over time. Either way, Yana was a completely different person (as was John Smith), with his own beliefs, values, etc. and although no one can really say for certain how he would have acted if he was aware of the consequences of opening the fob watch, I’m inclined to believe that he would have preferred not to embrace an identity that was completely at odds with his own.
It is true that conditioning is a huge part of what makes a person who they are, and assuming that Yana began existing at the age which the Master appeared to be (if you’re going based on old Who, that’s around fifty, right? New Who I would gauge to be around forty or so) then that’s a good twenty years of conditioning to go on, so I could see his “abnormal” personality traits being suppressed, while his more human side gets to flourish.
There was an awful lot of leakage from the Doctor through John Smith, though, through his dreams. I’d have to re-watch the portions with Yana to be sure, but I cannot for certain recall such a large volume of backwash (that is, of course, discounting the inventions that he makes, which are utterly brilliant). This could indicate a more sympathetic Master (unlikely), or it could mean a tighter lid on the machine that cloaked him, so to speak.
Now that I think about it, it doesn’t seem to me like John Smith was a construct- not really. The Doctor’s mother was human, so it’s entirely possible that he grew his human personality out of that side of himself, in a way. The Master didn’t have anything like that to work with. He probably just created his Yana persona by observation.
But that’s my point. Even if Yana was a persona that was completely fabricated, he still lived and aged and experienced everything as a human and was accordingly shaped into a real person - someone who was not the Master. I think that makes it quite tragic because when John Smith reverts back to the Doctor, he’s still part of him (the Doctor himself says this), whereas when Yana reverted back to the Master, he essentially died.
RE “leakage”: there seems to be a lot of it when the others begin discussing time travel and the Tardis. But we have to take into account the fact that we only really see Yana for a very brief moment in time, whereas we have much better insight into John Smith’s personality because of his diary (which he wrote in for months), extended discussions with other characters, etc. For all we know, Yana might of had dreams of his previous life as a Time Lord as well.