The Doctor shot Jack a look, asking for patience, before turning his attention back to the Master. He started taking of the Master's coat, deftly. "Tell me what's off," he said ordered. Very clearly ordered.
The Master looked at the Doctor like he was crazy. "Well, I don't usually doing around threatening people who aren't threatening me first, these days, do I?"
"Looked to me like you were cornered by a guy who had his hand on a deadly weapon, and trying to get him to back the hell off," the Doctor said, looking steadily at the Master. "Not what happened?"
The Master shook his head slightly, and closed his eyes, "Like I said, thought of him hurting Jack with what seemed like malice, and I lost my temper. I haven't been that afraid of what I might do in long, long time."
"You wanted to kill him, really wanted to," the Doctor translated. "Even though you think that would have been wrong."
"Yes," the Master whispered, eyes still closed.
"Hey, look at me," the Doctor said softly, nudging the Master head up, so the Master could meet him gaze.
The Master opened his eyes, looking wary, lost, and a little ashamed.
"You didn't," the Doctor reminded him warmly, before he kissed him.