go between
1. verb To move in between two people or things. The teacher quickly went between the arguing students to separate them.
2. noun One who serves as a messenger between two people or groups. In this usage, the words are usually hyphenated. I'm sick of being a go-between for you and Dad—can you please just talk to him directly?
go between (someone or something and someone or something else)
to get in between people or things, in any combination. The dog went between Mr. Franklin and the wall. The arrow went between Jed and Tex, injuring neither of them.