Realistically, I don't mind a player who gives advice to other players, and for the most part I don't see that as "playing someone else's character." The game is meant to be open and friendly, and quite often there's a lot of interplay that really couldn't happen if reality were invoked.
This is particularly true where characters are separated by a great distance, where there's no possibility of giving advice. Naturally, if the party is tight together, the giants are just over the hill and people are debating what to do next, it's perfectly acceptable that the player of the mage says to the player of the fighter, "Use your bow and hide, don't come out until they start ripping up the trees trying to find you."
Things get trickier, however, when the fighter has moved off to the left with the thief, and the mage is now eighty yards to the west hiding in the scrub with the ranger. I'm still generally willing to let it go, however, when the giants begin ripping up trees and the mage says adamantly, "Attack now. Now!"
I don't think the mage is standing up and shouting these words, though I can't blame a DM for reading the scene that way. If you want to get fixated on reality, you pretty much have to. I'm a bit more generous. It's the sort of thing that's going through the fighter's mind anyway, the mage is just enunciating it out loud ... and not every player at the table can express themselves as well in a given moment. Sometimes, having an expressive player speak the conscious thoughts of everyone at the table (who are all thinking, "Attack! Attack!") is beneficial for the enthusiasm and emotion of the moment.
So I'm willing to suspend the impossible for that reason.
Where it gets difficult is where one character is placed in a situation on their own, usually one that involves a conversation with an NPC, but sometimes where they have to puzzle themselves out of a mess they've gotten themselves into. What you want is for that player to feel the desperation of being there - and to feel the difficulty of showing themselves capable of overmastering the NPC or the situation in a manner that proves their worth.
In other words, it's an opportunity for a player to shine. For the less exuberant players at the table, this can be a critical moment in their experience as player in a D&D game. They're often the type that hangs at the back; who are happy to go along to get along. They love the game, they love smashing the enemy and watching their blows count in battle, but they're not exceptionally confident as actual persons ... they're quiet and shy.
This means that if there's a free-for-all interplay where strategy is discussed or the drama is unfolding, they're the least likely people to throw in their two cents. This does not make them bad players. Anyone polite, imaginative, and ready to step up when the time comes is a good player, even if they don't feel the need to dominate every session.
Those who do dominate a session, however, tend to be less comprehensive of the less expressive players. Wrapped up in the moment, they generally fail to recognize that others are there ... and as a DM, it's important to step in and - occasionally - shut people up.
Because you've let them off the chain on a lot of occasions, however (like with the giants), sometimes the decision to say, "no, shut up now, let them work it out themselves" comes as a surprise. And occasionally a bit of offense is taken. But it IS necessary for the drama to occasionally shut down some of the players in favor of others, where the intention is to keep the drama at a peak for everyone.
It won't take a lot of imagination for the reader to guess that the writer of this post is one of the worst imaginable for "playing other people's characters." I've never seen it that way; I want to live, and if living means that the mage not fuck up and deliver the fireball in the wrong place, I'm going to make it clear where that fireball should be delivered.
I had a situation Saturday where the party was fighting a host of orcs and the mage had set up to deliver a lightning bolt. Because there was tension, because there was a question of the party surviving, because there were a dozen targets and because the targets were color-coded on the battle map, the mage got a bit flummoxed and wound up discharging the lightning bolt into at least one orc who was known to have less than five hit points. Everyone was talking at once, giving advice ... and confusion took the day. And after it had happened, and after I had ruled that it couldn't be retracted, one of the players at least was seriously pissed.
I have two thoughts about that. First, yes, the mage goofed. I would have probably been pissed myself, had I been the thief watching it. And I would have wanted to explain carefully why the mage should not be stupid and do it that way again.
On the other hand, as DM, people ARE going to goof. In a real combat situation, people will fuck up. It happens. And realistically, no matter how many times you try to stop these goofs from happening, they just will. Emotions run high, there's a lot on the line, people are all talking at once and in the middle of that mayhem, people say "orange" when they mean "red" or they say "blue" when they mean "green." That's what stress does to us.
As the DM, I have to be the one not feeling the stress. I have to be the one who doesn't have anything on the line, and I have to be the one who has empathy for everyone at the table ... especially those who are less able to stand up for themselves. I have to shut down the player who is starting to ride the mage, I have to keep the air clear, I have to move the game along ... and I have to sometimes say to a player, "Shut up and let them do it."
If I let myself be as emotionally wrapped up in the game as the player, then I am the one that is fucking up now. There are parts of the game that I can enjoy, but that is not one of them. Being above the stress means making the game better for the players ... and being there to defend them, or set them back on track, and not let everything devolve into bitterness and backbiting.
If there is an argument going on at your table, and you're not stepping in to stop it, quit DMing right now. You don't have the temperament for it. If you have an opinion that either player is right, or that there's anything to be gained by letting them 'settle it,' then you have no idea about your purpose.
Never let players snark at one another. Never let anyone at your table make a judgement about if another player's action go unchallenged. Make your players understand you're not going to allow that shit. Make a player get up and take a walk around the block if you have to ... and if they won't come back, then good riddance. Your table doesn't need that kind of petty shit. BUT FIRST AND FOREMOST, give them a chance to cool off. Don't get worked up yourself. Remember, they're feeling stress. They're not really bad people, they're just really, really involved with their characters. That's they only reason they're feeling bitter or resentful ... and given a chance to step away, reassess, what have you, they'll most likely come back apologetic and considerate.
Let them participate, but only up to a point. Let them get excited, let them cry out in anguish when one goofs or fucks up. But step in there and don't let them dwell on what's happened. Move them onto the next round and keep the battle going. They can sort out who made what mistake when its all over and they've won or lost. If they've won, its all going to seem a lot less important.
But get in there. Get in your player's face. Draw the line for them. They won't draw it for themselves. Don't be a jerk. Don't judge them. Just stop them from what they're doing and make it clear the line is there. Then smile, clap them on the shoulder and keep going with the game.
Managing people is all about making them feel good about themselves when they feel like shit. This is very hard to do when they're doing something wrong. You've got to make them understand it's wrong, and that you understand perfectly, so you can build their self-esteem while making them change. It's a skill that as a DM you must learn, or in the end your games will always descend into chaos.
I have said that the DM is not a player. You can't afford to be. There's too much for you to do.
There are those who will not be able to reconcile the above advice with the person they believe writes this blog. Something that I cannot seem to make people realize online is that there is a difference between me as the person, concerned with the feelings of people I work with and whom I love, and the cold, harsh opinion I espouse here. Both of them are true reflections of myself. I am always sincere. I don't love nor agree with everyone, and I attack those whom I do not; but because you personally don't find yourself able to reconcile your beliefs or actions with mine doesn't make me a monster. I'd be happy to make the acquaintance of most any of you; I'd be happy for the opportunity to explain where you've gone wrong ... considerately and sincerely. So long as it's understood that my position is that you ARE wrong, and that for whatever reason your being wrong is hurting the game, the people around you and the general wellbeing of the planet. On that account, there's really nothing I can call you that isn't called for ... so don't ask for tolerance. Don't say that you have your way, that your way is just fine, because I don't believe it is. And I'd like to see you grow up, educate yourself and come to the recognition of just why you've been a selfish, misguided doughhead all these years. That's all, no big deal. Lots of doughheads around. The difference between you and they is that you're a doughhead that keeps coming back to read this blog, and that means there must be hope for you. I'm not making any inroads with those fascinated with NASCAR. Do you see how that works? You're 100% in control here. All you have to do is never read this blog again, and I will never have another moment of influence over anything you think. It's all very simple.