I do several things to keep the player characters interested and invested in each other.
- At the start of the game, I insist that players coordinate backgrounds (subject to my approval) such that each character know at least one, and preferably two or more, of the other characters. In general, I prefer these connections be positive; the most negative I will usually tolerate is on the order of a friendly rivalry. In general, I also prefer that if you start from any one character, you can get to any other character by following these pre-arranged links. (In graph theory language, the players are all connected, although indirect connections are fine; the alternative would be two more more sub-groups connected internally but not to each other.) And finally, I try to ensure that each connection is more than trivial, but not necessarily life-binding.
So for instance, "We met in a bar twenty years ago and never saw each other again," is trivial. "We are cousins who are best friends and we are rarely separated," is life-binding and more than I look for (although it's fine if that's what they want.) Things like the following are what I look for, and/or what I've seen in the past:
- Our characters served in the same unit years ago, and knew each other, but haven't kept in contact...
- I served as a mercenary escort once, while he was travelling with his master from here to there; along the way, this happened....
- We weathered the siege/plague/earthquake of wherever together some time back....
Now, some players are genuinely not wired that way-- if you ask them for backstory, they freeze; if you given the one, they can't connect to it. When I run into a player like that, I have to respect that, but I try very hard to get everyone to adhere to the guidelines.
That does not directly solve the problem. (It actually solves the problem of getting the characters all on the same page at the start of the game.) But it does often give me enough to work with to do the following:
- With enough insight into character backgrounds, and with overlapping backgrounds, I try to give every character an mid-term to long-term goal or plot arc, and then I try to modulate that by giving at least one other character a minor to moderate interest in how the first character's arc plays out.
It's important (to me, for the games I want to run) that these arcs not be strictly opposing: If one character has sworn blood-vengeance on an NPC, I won't give another character the goal of keeping that NPC alive. But I might give another character the goal of getting something from that NPC before his death, or getting the NPC to do something, etc.
And I also try to modulate this in another direction by giving other characters-- ideally, not the same one-- influence over the plot lines. So continuing that thought:
- Player A has sworn to kill Sir Odious, his parents' killer
- Sir Odious has information that will help Player B in her quest to do something else
- Player C knows someone who can be bribed into giving up information about where Sir Odious will be
In that way, for each of the various player sub-quests going on, at least one or two others will be involved somehow, even if only at the periphery. Ideally, Player B has some motivation for something to happen, and Player C has something he needs-- something at least moderately costly or risky. They are invested.
One thing I would not do-- at least not again-- is what you tried:
I've had players create characters (with backgrounds) completely secretly from each other with the hopes of allowing the character interaction to be heavily role-played at the table. Didn't work because of very incompatible characters.
I've never done that, specifically, but I've inadvertently done similar things and it never worked well. It seems like it should work, especially if you pattern it similar to what I've outlined above, but there's a structural weakness to it: If the players, starting out with the relative blindness of only knowing their little part of the background, they just might not see those connections you built in for them, and won't give themselves the incentive to start sharing information. And if your players were the sort that would do that naturally, you wouldn't have to go through these acrobatics in the first place.
The group I play with used to have problems that resemble this, and I think a lot of the issue is that you're asking slightly the wrong question. Specifically, it looks to me like your group gets into a situation where you know what the current situation is, but not how you got there; the argument is high stakes because you're having arguments about what happened in the past because it's really a proxy argument about what the current situation means.
In your example, you all agree on what the PC said; what you're really arguing about is whether the NPC ought to be insulted.
And the reason it's really hard to resolve is that you're treating actions and reasons as severable: players are saying "the reason my character did X was because I thought Y", and your group is committed to saying that they definitely did X, even if Y wasn't true. The problem with settling facts without regard to motives is that it leaves players feeling like their character's integrity was violated: they wouldn't have done X without Y, and now they're left with a character who apparently did it anyway.
What worked for us was recognizing that they're not severable: if someone did X because of Y, and your group clarifies that actually Y isn't true, it also follows that the character didn't do X.
There are two techniques that helped us that might help you:
Recognizing that the important thing is finding a shared consensus, not the true story of what happened. Ignore the question of what actually happened; have everyone go around and explain what they think happened and why. Then ask: what does everyone need to be true. Does it matter that that the other PCs weren't talking, or could you rewrite the history so that they were talking? Could the PC have insulted the NPC, even if that's not what the player was expecting? Put aside entirely the question of what actually happened; here are a lot of reasons people fall out of sync about that (people misunderstand, they mishear, they get distracted, they forget things). Litigating what actually happened isn't important; having a mutually acceptable situation going forward is.
Being prepared to modify what happened ("Okay, my PC wasn't talking, but sure, we can decide that actually she was in the middle of saying something") or, if necessary, backtrack: "My PC wouldn't have said that if the NPC wasn't talking over people, so let's back up to when the NPC started talking and take it from there". It took some practice for us, but we got better over time at finding ways to salvage content: at saying "I really liked what happened when it seemed like you insulted the NPC; is there something that could have happened that makes sense for your character, but still makes that happen?"
Best Answer
A note: While this is a system-agnostic question, certain systems (ex: DitV, FATE, Paranoia) are much better at handling this than others (ex: Any D&D system). Some games are even focused entirely around CvC conflict (En Garde, Everyone Is John, etc). For the purposes of this response I'm going to assume that in this game the party is all on the same 'team'.
As usual, my first recommendation is that you make sure everyone wants to play the sort of game you're after. Sit down with your players (as a group or one-on-one) and see how they feel about the idea of inter-party conflict. The beginning of a campaign is a FANTASTIC time to discuss changes in tone like this, especially if you start one in a system that encourages inter-party conflict. Encourage openness here. If they all seem to want to try it, continue. Otherwise, I recommend you back down, because trying to make this sort of game happen with the wrong group of players is an excellent way to hurt peoples' feelings.
Now that we've got everyone on board, the first thing to do is explain to your players that it's OK (and in fact, encouraged) for characters to have arguments, disagreements, romances, etc. Many players, especially in mono-gendered groups, will likely feel uncomfortable with the idea of pursuing another character in a romantic fashion, so you may wish to leave that off the table until they get a little more comfortable with these forms of role-playing. Again, if players seem reluctant, back off.
But if your players are up for some conflict, a good way to start off is by encouraging PCs to keep secrets and make autonomous personal choices.
Secrets
There are two types of player with regards to secrets. The first type prefers to know only what their characters know, to be able to plot on their own and pass notes with the GM. The other kind prefers to be completely open out-of-character and only keep secrets in character. Naturally there is a third type wherein no secrets are kept, but we're assuming against that for this exercise. Try to get everyone to use the same system. In my experience, it is easier to get everyone to have a good time and cooperate to make shenanigans fun when everything is out in the open for the players, but the characters keep secrets from one another (ex, you might tell the ranger, "You see the pixie messing with the paladin's blanket!" in front of the entire group, and leave it up to her to decide how to proceed). This helps to make everyone feel like they're in on the joke, and allows characters who are being tricked to have fun 'playing dumb' and going along with the gag. This is definitely the safer bet if you're afraid of people's feelings getting hurt.
Encourage the players to leave 'hooks' in their characters, especially ones that lead to something they may want to avoid telling the other party members. "I'm looking for my long-lost father" is an OK character hook, but "I'm looking for my long lost father who I last heard was involved with the Evil Empire" is more along the lines of what we're after. Regardless of how interesting you find your players' hooks, be sure to bring them into the campaign in some way. Work with your players to make their stories and hooks work with your setting. Feel free to entwine the characters' back stories, especially in ways that create conflicting interests and goals. These back stories, and the way they bring the character's personal journey into the focus, will help not only to create conflict, but to make the PCs and the world feel more alive and fleshed out.
What you will (hopefully) start to see is a divergence of party objectives (assuming your party is not entirely composed of Lawful Good Paladins of the Righteous Truth, in which case you may wish to re-think your campaign goals). Previously, the entire party's objective was to 'win', but over time, keeping secrets and personal goals should naturally branch characters into a number of side objectives (don't let the party find out about my stealing from our employer, redeem my father even though he killed my friend's son, hide my alcoholism, etc). Now that we've decoupled the party objectives a little, we can sprinkle in some moral choices.
Autonomous Personal Decisions
As you're designing encounters, feel free to leave situations which are morally ambiguous, or in which the party is likely to be divided. If the paladin goes along with the party's decision to loot a tomb, or if the by-the-books cop has no problem with the party's decision to lure the big bads into a large open area filled with civilians for the big shoot-out, feel free to ask them if that is what their character would do. Likewise, feel free to encourage the pixie to play practical jokes, the scoundrel to be a scoundrel, and offer the hitman the occasional 'job' to help pad his bank-roll. Allow your players some autonomy from the group's decision. While splitting the party can get very messy, it is OK for characters to do their own thing every now and again, or for some characters to sit out from a plan they aren't comfortable with.
If someone does something remarkable, awesome, or highly in-character, award role-playing XP. Did the high-strung businessman just express his concerns with the brutish thug's methods? That's worth some role-playing XP. If the thug reacts in character, feel free to toss him some, too.
So now we're all acting of our own accord. How do we keep things in control?
Again, everyone needs to understand the difference between the PCs and the players. Make sure the group is clear on that.
When somebody starts shenanigans, look around the table. Is everyone laughing, or is someone uneasy? If players are uncomfortable, especially if a player feels like she's being picked on, it's time to either talk it out as a group or drop this play style.
Finally, make sure everyone has their time to shine. Backstory missions are awesome at making people feel important, especially in small groups. Make sure everyone gets a turn at doing something their character cares or feels strongly about. Make doubly sure that each player feels like he or she is contributing both to the story and the party. And finally, ask for suggestions, comments, etc. after the session. This is a great time for the players to bask in how awesome they were, or to point out parts of the game they loved (or hated!), what you should do more of, and what you might want to lay off on. Try not to take things too personally; if a GM reacts well to criticism, players will feel free to be honest, and everyone will have more fun in the long run.
Most importantly, have fun with it! Laugh with the players when the entire party is embroiled in a terrible snafu, or when the halfling gets caught shoplifting and spends a quarter of the session running from the cops! We're all here to have fun, so go with it!