"Oh?" The Master raised an eyebrow. "Am I now. How.. different. Clearly not my own reality, or you would be more aware of what I am." He watched her for a long moment, one hand resting on the table between them, the other loosely holding his glass.
"Regeneration is a Time Lord's way of cheating death. A new body, reshuffle the personality - the core is the same, but some of the other traits change. Tastes, quirks, foibles. Just one more evolutionary advantage we have over the lesser species."