Caitlyn kissed Jack back and caressed his face. "And that is unthinkable. So thank you for rescuing him." She said looking and seeing that 'Harold Saxon' had a history on Earth. "Well, let's think about this for a moment or two. Did you notice another Time Lord here? Is there a way for your people to lock away who they were, create another persona, be him a while and come back to who they used to be?" She asked theorizing on what had caused the Master to have such an excessive history. She didn't know anything about Time Lords neither, but if she were to hide away from her own people, she'd change her whole background, even going as far as changing what she had been to something else in order to change, becoming one of the locals and creating a past.
That was a good question, Rose thought as she looked at the Doctor curiously. She never saw him use such a thing, but him being as old and coming from such a smart race as the Time Lords, she didn't doubt that what Caitlyn had asked could be possible. Not that she really knew what the Time Lords were like as she only met him and the Master, being a psychopath bent on destroying the world, she figured he didn't count as one.