hang behind
To linger or remain rather than advancing or moving on when other people do. Hey Lisa, hang behind for a sec—I want to talk to you about something. The rest of the tour group moved on, but I hung behind to study the painting a little bit longer. No hanging behind the group, OK? I don't want to lose anyone.
hang behind (someone or something)
to stay behind someone or something. Don't hang behind us, please. Come on up here and walk with us. Fred is hanging behind and may get lost at the next turn.