And if not, at least this way she knew nothing was going to come up behind her.

Then she felt, rather than heard, someone come up behind her.

He heard his chief of staff come up behind him.

I stand back as the others come up behind him.

She had not heard the woman come up behind her.

Then I saw that he had come up behind her.

She stopped to hold the door open because someone was coming up behind her.

Which was why he hadn't heard the man come up behind him.

I didn't hear the second one come up behind me.

To get to her at all, he has to come up from behind one of us and go past.