In any sort of tabletop gaming, you wind up with a gamemaster. The point of the affectionately nicknamed GM is partly to come up with adventures and plot hooks and so forth for the adventuring party, but here's a secret. Most of that stuff is done in about an hour, frequently stealing liberally from whatever genre-appropriate book, television series, or video game the GM is partway through. (We're not so naive as to assume you won't notice, but we are so pressed for time as to be certain we don't care.)
The real meat of a GM's active work comes when the game starts and there's a dispute about the rules. In some groups this can take most of a two-hour session to finally crop up; far more frequently, it occurs within the first five minutes of play. This happens with absolute certainty if the players are all males between the ages of 14 and 17 who have realized the game rules don't stop them from killing the shopkeeper and taking all his weapons for free. And this is when a gamemaster makes a ruling, and the group grumbles slightly but accepts it as fair and consistent.
If you're running a group RP event, you need to arrange for something similar. Not the ability to assault shopkeepers and take their goods, but a reasonably neutral third party -- or at least a consistent and mature third party -- to make sure that when problems arise, someone is there to keep things moving. Guild leaders and officers are often perfectly suited for the role, as are the people who come up with the arc in the first place.
Now, system debates won't come up in an MMO. What will come up are debates as to the exact sequence of events, debates as to what one character would or would not have access to in the land of NPCs, and so forth. A good arbiter will do more than simply settle these debates; he will also be responsible for making sure that no scene overstays its welcome and no player is without something to do for too long. If conversation is flagging, he picks it up. If there's a lot of confusion, he tries to clarify.
All of this can be hard to do from the mouthpiece of a character, of course. Characters best suited to the role will generally have some degree of esoteric knowledge, and they may very well have a leadership or mentoring role to begin with. In the best cases, there will be more than one person working as an arbiter and sharing notes with his fellows, allowing people rotating turns in the driver's seat.
Some groups are just better suited to some stories than others. If your friends want to do silly and light-hearted character-based roleplay, your epic tale of love and betrayal is going to leave them a bit cold. Get a sense for what sort of roleplaying each steady member of the group is going to want to take part in, and try not to rely on people playing roles they're not comfortable with. Obviously this goes back to communication, but often times a little thinking will make some issues clear.
Beyond even that, however, you want to balance storytelling with the need for everyone to have some hope of getting involved. Not everyone has the same batch of free time available every single week. People can run late or not feel up for roleplaying on a given night, or even just forget. At the same time, you want to reward participation -- people who have been a part of an arc from the beginning should feel like they've got a bit of an edge, that they've taken part in the whole story and would get an achievement for it if the game allowed it.
From personal experience, I find that the best way to pace things is with small arcs of two to four "sessions" each, each event taking between an hour to two hours. That's not a huge stretch of time, it keeps arcs from becoming overly cumbersome, and it means that if someone missed the first few installments he's not going to be left behind, as the entire guild takes part in a storyline spanning several months. Other groups might vary -- you might have excellent attendance and can run something forever, or you might have a wildly rotating cast that forces each night's events to be self-contained.
One of the jobs for the arbiter or arbitration team will be making sure that things start more or less on time. Set a start time, set a grace period if you so desire, and make sure that when that grace period ends the group is away and flying. If someone shows up late and absolutely must attend, his arrival is in his hands, not yours. While it's going to lead to some slightly ruffled feathers, that's counterbalanced by the huge benefit of players knowing what will happen when they log in. Arrive for the week's roleplaying event at 8 p.m., and you will be off and going until 9 -- and you can plan around that in the future.
There's a lot to be said about plotting a variety of events. What you put together that works for a light-hearted night of comedy is probably going to run into some issues if ported directly into a serious storyline. There's so much to explore here that it almost merits another column or two on genres, though some of that runs into the realm of the over-specific.
A good rule of thumb, however, is that with some knowledge of how many people are likely to attend, there should be an opportunity for everyone to do something. This is partly an issue of arbitration, but also an issue for which you want to take pains to ensure that there will be several different chances for neat things to happen. If everyone's just standing around in an area, something ought to happen that pushes someone into the limelight.
Even more important, though? You are not plotting a hard-and-fast event. You are giving yourself a loose framework of what will take place for an evening of roleplaying, something the players and you may all deviate from quickly. Think on your feet, react to changes, and roll with them. Which is just good practice anyway, right? Right.
That's it for this week, and as always, I'm eager to hear what you think. Feedback can be left in the comments, or sent off to firstname.lastname@example.org. Next week is a bit of a mystery to me, although I have a few ideas kicking around.