"You've yet to see me ruthless, Jack," the Doctor replied as the TARDIS shot out of the vortex. "But if these are the people who responsible for all of that death, of Ianto's death, ooh you're going to see it. I'm not the man you once knew, Jack. Are you prepared for that?"

If Rose could see him now she'd be horrified, but not even that thought was enought to stop him anymore. He was too far gone, too angry and a bit addicted to his own power now.