What Bills says: You are the stupidest idiot ever!!!
What Bill means: I love you, you stupid old overbearing crazy-ass alien and I swear by my magnificent hair that you will be whole again. I will do anything for you, you moron. Now shut up and let me save you.
•They must personally know the Doctor.
•They know about Bill.
•They can play musical instruments.
•The Doctor must not consider them as a threat to him since he opened the doors to see them.
•The Doctor made a promise to someone that he will guard whoever is inside the vault.
•The Doctor tells them stories???