Professor Yana (Derek Jacobi) begins to remember his true identity in Utopia (2007).
Professor Yana is the Master. We all know that’s the - brilliantly executed - tw ist in this episode. We also know that Professor Yana doesn’t become the Master until seven minutes from the end, so it could be argued that Utopia isn’t much of a Master story. But this overlooks the fact that Yana is as much the Master as John Smith is the Doctor in Human Nature/The Family of Blood (2007). As a result, he gives us a fresh insight into the Master’s nature.
In particular, it seems that the process of using the chameleon arch to become human also removed whatever it was that made the Master turn evil. Is this because it erased the memories of a traum a that set himon the dark path - or is it because it’s the Time Lord part of his psyche that makes himbad? Either way, Yana is a glimpse of the man the Master might have been had he not stared into the Untempered Schismas a child.