Hi. Some times you'll exclaim something like this: ---Awesome! ---Danger! Or perhaps what is being addressed is not whom you're talking to: ---Oh my god, a bike! ---Bruce! He can tell them the answer. Or sometimes you'll want to stress a specific part: ---It's green. Green! I hate green. ---That man was/you are tall! Or, when cheering: ---Roger! Roger! So here is the question: which case should be respectively applied if a Roman was actually going to do so? Vocative or nominative?