I have a little scene where one of my NPC's is yelling at a guard in Riften. The only problem is that the guard patrols sometimes, meaning my character stand there yelling at nothing like a madman. Can anyone tell me how to figure out exactly which guard stands there, so I can alias him and just make him stay there for the duration of my scene? Unless someone has a better solution.

The marker the guard stands at isn't linked to anything, and there are like 60 guards set up in the field in the city. How do I know which one is the right one, if any of them?