The Master, quiet until now, dug his heels in to resist being brought into the TARDIS. He also growled. He was scared.
Jack yanked him through anyway. "There's not much to tell. I saw him on the street, went up and introduced myself. Talked to him long enough to find out he's got a precussion section in his head and recognize his bracelet as a restraint system. I offered to take it off for him, then I did. Once I was sure he wouldn't get electrocuted to death if he wandered too far I cuffed him, gagged him, and brought him here. "