stay behind
To remain in some location from which one or more other people have departed. We'll need someone to stay behind to give Jeff and Tina their keys to the lodge. The rest of the group decided to go on a hike, but I stayed behind to read my book by the lake.
stay behind
[for someone] to remain in a place when others have left. I will stay behind and tell the late arrivers where you have gone. Fred always stayed behind to clean up.
stay behind
v. To remain in a place that others have left: I stayed behind because I had too much work to do.