Hey there.
I'm currently in a pathfinder game with 5 other players. We got into a situation where our characters were all together within arms reach of each other. One of my Co-players decided to chase after an NPC to go bash it's head in. Once he announced his action, my other co-player asked the DM if he would be able to stop him based on his own alignment after about 30 seconds of checking the rule on this the original player said "it doesn't matter, I'm already down the street after the NPC. Your not near enough to stop me".
So my question is: while roleplaying, if a player spontaneously makes a decision to run off, do the other payers have a chance to take their time to react to the situation? Or if he says he's already down the street, he's actually already there and we can't take time to react to his decision? Also should there be a kind of "initiative" while making roleplaying decisions?