Courtesy of Digital Spy (my bold):
John Simm has said that The Master is desperate after his death and apparent resurrection in the upcoming Doctor Who two-parter 'The End Of Time'.
The actor told Radio Times that the character he first played in series three's 'Utopia' had been transformed into an "emo Master" for the new episodes.
Simm said: "This is a Master who's lived and died and now lives again - although he's seen healthier days. He's desperate, and desperate means dangerous."
Outgoing showrunner Russell T. Davies added: "It's personal for The Doctor. The Master is his enemy, his opposite, and yet so tantalisingly close to being his soul mate.
"There's something epic about their sheer existence - the last two survivors of an ancient race. It's a clash of the titans. Both of them, heading for death, and yet both determined to survive - at any cost!"
The final episodes of Davies's tenure as the programme's head will also see the farewell of David Tennant's Tenth Doctor, who will be regenerated into Matt Smith's eleventh incarnation of the Time Lord.