After one of the recent table top sessions, our group dissolved into a discussion about the differences between fiction and reality. Now this is something that comes up a lot in writing advice books and blogs, but it basically boils down to this: fiction makes sense, reality doesn't have to. Now, when it comes to games there is something else you need to remember: it needs to make sense to the players when it happens, not after.
A Case In Reality & Fiction
To illustrate this point, let's take a look at a problem and go through how it would work in reality, how it would work in fiction, then what the reaction might be from players. So, let's say that we have a character named John, and he's been attacking and messing with the mob's business. Now, obviously the mob is going to respond, and this is the not screwing around club, so it is going to be serious.
In The Real World
So, in the real world here is how it would go down. John would be walking down the street one day when out of the blue he would be surrounded by 3-4 people with an overwhelming amount of firepower. This could be handguns, assault rifles, or shotguns depending on how much John has done, or how he worked. The point is, everything is free and clear, and then John is dead. Usually right at a moment when he is either the most exposed, or feels the safest. It is quick, it is clean and it is brutal. It is also totally unfair, and comes without any warning.
Now, in fiction this would happen much the same way with the following change. We would likely get a scene explaining how it was going to go down before hand, or John would somehow miraculously survive and find out afterwards that it was in response to his actions. The point here is that at some point the audience would be clued in to it making sense.
Now think about how this would work in a game. You've got a player, and he thinks he's doing well. He's on the attack, he's making the moves, and as far as he knows, he's covering his tracks. He has no reason to think that anything is going wrong, and then while handling something else in game, the GM just jumps him with four guys with assault rifles.
At the very best, if John survives, he is going to think that the GM is just trying to kill his character. The attack comes without warning, and he has no idea where it could be from. Even if you explain the fact after the attack, it is still going to have a foul taste. Why? Because at the moment it happened, it didn't make sense. It was realistic, sure, but it didn't make sense.
Consequence Driven Gameplay
This then becomes the problem you need to know about if you are trying to have consequences. Sometimes realism needs to break to make things more fun. It might be more realistic for that pissed of sniper to just assassinate the player from a half mile out with no warning, but that isn't fun. To the player there is simply a sudden and brutal change from "I'm having fun playing my character" to "my character is now dead."
At the worst, the other players may also feel this way. It could come across that you were actually gunning to hurt that player - or just kill a character that was messing things up for you. To an unprepared GM - and how could you be prepared for this? - this can also hit very hard. After all, the GM was trying to do something fun, and actions do have consequences, so why is it coming down so hard?
How To Avoid This
The key to avoiding this is to warn the player. You can handle this two ways. The first way is to warn the character. This could be a contact telling the character that there is a bounty on their head, or just a heads up in general to watch their back. Just make sure that it is clear, their actions have been noticed and hard times are coming. The other way to do it is to tell the player. Now, you don't have to give the player all the details, but just a heads up will work. Do it clearly, and in front of the other players. Even if it is just something like "You know they're going to be coming back at you for this crap, right?" can do wonders. If nothing else, it tells the other players that something is going to come up, and that you are paying attention to what they're doing.
Now, there are other ways to handle it. Such as giving a cutscene of the hit being ordered, but I generally don't like doing that unless I am specifically going for a cinematic feel. Sometimes it just feels odd to happen randomly. So, if you want to do this way, then make sure you do it for other things as well.
Aside from that, communication is always key. So keep that in mind, and you too can avoid blindsiding yourself and your players with bad stuff.