Fred was confused. Well, not so much confused, as confused. She didn't understand how this woman could just walk away; it made her think a little of Angel, then thinking of Angel she thought maybe there was something going on that wasn't so obvious.
"Millie, wait! You can't go home. You just saved his life. And, you gotta do something for her!" Fred looked up at Simon who was certainly feeling uncomfortable about all this. He had taken a few steps away, but the sounds of authorities, aka sirens, didn't let him go to far - someone had to explain the situation.
"You have to say 'thank you'." Fred looked between the two before looking at the Doctor.