I've been doing a lot of self assessment lately, trying to find things I can improve upon and things that I genuinely like about my GMing style, and one of the things I came across as being a bit too vague is something I've told my players a number of times when they were preparing for one of my games. The saying goes like this: anything you don't define in your backstory is fair game for me to meddle with and define. The idea behind it is simple, that if you leave something open - or hooked - I may use it. However, while this is fairly common for a GM to do, the full meaning behind it isn't always well known. Today, I want to talk about my view of it.
It Is Still The Player's Character
This is the biggest thing that I've seen some GMs miss out on when using this strategy. Sure, maybe you wanted a two page back story that gave the basics and some key details, and that player only gave you a few paragraphs with a lot of blank space in between, but that doesn't mean the player doesn't still own the character. There is filling in the white space and there is filling in the white space such that it affects the core concept of the PC or would have an otherwise huge impact on the character's personality.
For example, if due to the style of writing a back story has the PC has left it vague why something was done, or whether or not something was done, doesn't mean that you can define it and not let them know or consult with them on it. Why? Because this has an impact on the player character's life. Now, there are ways around it sure, but you need to be careful about that too. Any time you are linking to something major in a character's background - especially when it directly involves the PC - you want to talk to the player about it before hand.
And by directly involves the PC I mean that the action you are referencing in the past involved the PC. So, having had the shadowy organization have the PC kill someone because they wouldn't sleep with the boss - but the PC didn't know about it - would be fine as there is a layer of removal from the character. Having the brother of someone the PC killed show up looking for the killer is fine, because this is a consequence that doesn't directly involve the PC in the past. The target had a sibling, doesn't affect the PC before game time so you're good. However, having someone the PC killed come back because they weren't really dead does directly affect the PC. For one, the player could have a different idea in their head about how the person died, or the player may have killed the person in the backstory to specifically not have to deal with it in game because that wasn't a desired story. This doesn't mean you can't do it, but you should talk about it with the player first. At least get everyone on the same page of what happened before it shows up in game.
Sneaking Through The Cracks
Now I bet some of you more ambitious and wily GMs can already see ways through this, right? The person pretended to be dead, it was a clone/decoy, etc, etc. These can all be viable ways to do it, but you need to be careful with these too. Do it too much and you are committing a party foul: you're modifying the character to fit your game rather than your game to fit the character (more on this tomorrow.) Still, you can sneak things through this a few times, but it does still take some work on your part and some cooperation with the player.
To use the above example, say you wanted to say the person faked their death which is why the PC thinks they did the deed. This is great, unless the player is going off the assumption/statement that they make all their kills by detonating the head of their victims, or double/triple confirm kills. Doesn't mean you can't still work around it (clones/decoys are great for these) but it still takes some work.
Hidden Details Are Awesome
On the more positive side, and like I said above, anything that doesn't change the world from how the PC perceived things then is fair game. This can be hidden agendas, hidden alliances, and hidden motivations for things going on. The group the player worked for was secretly the good guys? Golden! That evil dictator the PC assassinated was actually a setup fall guy who was working for peace? Go for it! The person who told the PC that their brother was dead was actually lying? That's fine too.
However, even here you want to be careful. Again, too much and you begin to invalidate the player's control of their own character, modifying things to make the player play into your own plots. This is a case where less is more. Touch on it here, hint at it there, but ultimately try to work with what you were given. If it isn't enough, ask the player for more.
This still leaves you with a lot of room to fill in the blanks. Running with our assassin PC, if they simply said they ran "numerous ops for a few years" you can still use that to make connections with NPCs, even if on the fly. A little "you remember you did a job in Burma with this guy. Things went smoothly, you went your separate ways after and it wasn't really much of anything. Still, you remember she favors a blade and is a big fan of blood" when introducing another NPC can be a huge boon. It wasn't in the PC's background, doesn't affect their past, but it does a great job of grounding the PC in the world and making a connection to the NPC in question. Afterwards you can talk to the player and see if they want any special details about the mission made up or not. Everyone leaves happy, and you've made your game world feel a little bit more real.
Leave Room For The Player
The last thing I want to touch on here is that when you are filling in the blanks of a PC back story you want to leave room for the player. Some players like to leave gaps for them to define later. The Private Eye that doesn't mention being a family man anywhere in his backstory, but then gets struck with the fact that he had - and lost - a family a while back. Characters can be very organic things. They grow and change as the game goes on, and often a player won't truly know who they've made until you're 3-4 sessions in. Some players know this and so they leave themselves room to fill in their own holes later on in the game. This can put the GM and the player at odds when they are both trying to define the same thing at similar times. Remember, the world is yours to play with, but the character - the PC - is the sole domain of the player. If something they want is game breaking, you can discuss it with them later, but that doesn't mean you get to run rough shod over them with what you want their back story to actually say.
I'm curious what everyone who reads this thinks about this practice. There are a lot of - from all evidence - great GMs who frequent here, and I'd love to get your input. How much do you play with your players' back stories? Do you prefer to leave them a lone? Sound off in the comments.