"Does he now?" he asked, turning his head sharply to look at her. "He spends his time running.... Running away from everything that ever haunted him and now he is trapped and he can't run. He can't hide from me forever. There is more than one of him here" he pointed out. The Master was such a cruel, poisoned man. Bitter to the ages past. He had come to realise that not even sacrifice made a difference. He would always be treated the same way.
"You however..." he said slowly. "You contain knowledge.... You know things. You could help me... couldn't you?" he asked her. How could she not? She was the TARDIS! All those years, all that information. Time and space, all things possible and all things that should and should not be, locked away inside her. He had to know if she could help him. He needed to know. Before something snapped inside him, before his madness consumed his mind even more so.