So I was talking to my brother earlier today, and he asked me a question, one every Dungeon Master, Storyteller, or Game Master needs to have an answer to. What happen when your players decide to off the quest-giver? Some of you will have to deal with this constantly, with the perpetually meandering party who takes your carefully scripted campaigns and perforates them until all semblance of plot has drained into the muck, and some of you just have that one player with the character sheet no one is allowed to look at who’s totally not playing an assassin this time guys, for real.
Regardless, at some point in your life, the players are going to lob a fireball at the king, stab the kindly old mayor in the neck, or pull pistols on the crime lord. And you are absolutely not going to be expecting it. So, back to the original question, what do you do?
First things first, you give them an out. Always drop the “Are you sure?” when the players have decided they’re going to do something that will get them killed. If your players are half as smart as their characters, they’ll at the very least think twice before offing that guy. They’ll probably still try it, especially if they’re new, but you gave them an out, so your hands are clean now.
Second, make them roll for it. If they’re trying this sort of thing, they probably just rolled out of fighter college and think they’re top dog, and their chances of pulling this off are ludicrously low. They can take their shot, but they have to earn it. Plus, if they botch it, no harm done. Have them get beaten by guards, throw them in jail for the night, fine them, but you can get back to the important business of making your players dance for your amusement.
Third, let’s say they pull it off, or near enough. The rogue crossbowed the king in the eye, the little psycho whose mom you owe a favor threw a satchel charge at the president, or they snuck a disassembled LAW rocket into the crime lord’s mansion. Now you’re in a bind, because they cannot be allowed to get away with this, but you can’t listen to your first instinct and just drop rocks on them until they die. This leads to angry players who never want to play with you again. Of course you’re still going to kill them, mind, just not that blatantly. If your important plot person had bodyguards, this step is pretty easy. Roll some dice behind your screen (you better have a screen, even if it’s just a binder), and then tell them the guards killed them. If the important and now deceased NPC didn’t have any guards (what’s wrong with you? You put a defenseless NPC next to the players?) then you need to have someone nearby who can call the guards. City, military, royal, whatever, somebody yells for them and the players get killed.
That’ll learn ’em! Remember, give them an out, and roll enough dice that it seems legitimate when they die. And maybe next time they won’t be so stupid.