Numb3rs Fanfic Finders

Hey there new here and hope that people are still around cause I am getting desperate to find this fic.

So I am pretty sure this fic is on either AO3 or Fanfic since that is where I do most of my reading. (I am also pretty sure that the fic is marked as complete since that is also all I really read)

What I remember is that Ian Edgerton and Charlie are dating and Don doesn't really take it well cause he thinks Ian is going to get bored of Charlie. Somehow that got to Don comparing Charlie to a target in Ian's sight and getting bored of it and Ian answering that Charlie wasn't the target that he was the gun. I know that isn't much to go off of but I can't remember what else was there.