[Ben Dawson]

I've got an explanation for the drumming in the Master's head, he said "ever since he was a child, he heard the drumming", as Yana, he said that "he had been found as a naked child". My thought is, the young Master we saw, was actually the reborn Master (you know, when the Time Lords brought him out of the Eye of Harmony, remember, Bruce's body couldn't sustain him, it's only right he would gain a new one). And it was the "reborn Master" that stared into the Time Vortex.