So your players got themselves a shiny new copy of the PHB2, and they are dying to try it out… great! But maybe the problem you are facing as a DM though, is that you’ve got your story on track, the PC’s involved are part of a greater tale within the world you’ve crafted, and you’ve got visions of your BBEG getting pummeled by the characters you’ve been playing with for almost a year now. Not a problem for the creative DM… introduce an adjacent storyline!
Explore different paths in your campaign with alternate parties.
This could be an interesting experiment. Every other game session, the party can play the alternate characters they were dying to roll up out of the PHB2, and you can devise an alternate storyline, withing your world, just for them. It can even take your plot in directions you weren’t even imagining.
Let’s say the original party, Party A, was being sent by The Council of Elders on their missions. The Council of Elders fears that the Wizards of the Broken Tower, a primordial magic using cabal of wizards will one day gather enough power to take over the world. The Wizards need the Amulet of the Abyss to finish a ritual that will grant them this power. Maybe Party B can be hired by the cabal, (under fake assumption) to find the Amulet in the Abyss. This could be Party B’s 30th level goal, they (the characters, not the players) believe they are recovering the Amulet to keep it from being used for evil). In the end the parties both realize the threat the world faces and you can craft an ending to your campaign that has them both be heroic and save the world from a catastrophic primordial uprising or something. Party A has to do this… and Party B this… maybe characters can even cross parties.
Perhaps you guys have been dying to run paragon or epic tier adventures since your main guys are still in heroic. Well, here’s your chance. The stuff that maybe you expected to happen “off-camera” can now happen with an alternate party!
Another idea is to let in on parts of the the plot one of your players who has been dying to sit behind the DM screen, so he can run Party B through the alternate quest. You get to pick up a character sheet and play while still pushing your story along. Everyone wins! He may even come up with stuff you wouldn’t have thought of.
I’d love to know if any of you more experienced DM’s have ever run something like this before, and your experiences with it!
www. Newbie DM .com 
Rob G
May 2, 2009
Have each player make 2 characters. When not in an adventure (not in a skill challenge or combat) let the players have all the characters present. As soon as the pcs go off to adventure (skill challenges and combat) have the pcs take only one character and think of a good reason the other cannot come (staking a place/person out, guarding something, taking a message, working to earn keep, sacting as look out.)
Think of this process like the familiar passive/active mechanic.
Lurkinggherkin
May 2, 2009
Newbie, you have more or less described the structure of my campaign which has been running since 1995. And yes, it works very well.
The only thing I will say is that we prefer to run chunks of plot in blocks of several weeks or even months rather than alternating on a weekly basis, because alternate weeks tends to disrupt the continuity somewhat – players would get their NPCs and snippets of plot info in a muddle if we switched from week to week.
rjbs
May 2, 2009
I do something similar, although I’ve had very few chances to put it to the test. I have alternate characters that are used when one player can’t attend. This means there are a few entire parties: the default one, and the ones that are played (giving back story) when someone has to go do something stupid like “attend a sibling’s wedding.” So far, so good.
Ameron
May 3, 2009
This is a great idea. It lets the players have back-up characters ready, just in case. Our group tends to frown on any side-track adventure using alternate characters because we want the main game to keep moving forward. If the alternate characters are in some way still tied to the bigger story arc, I think we’d be more likely to try this kind of secondary game. I’m going to ask my DM to read this article and see if he’ll try it. Thanks for the suggestion.
Jason
May 11, 2009
Ha! I was just thinking about doing something like this for this week’s upcoming game. It’s been a month or two since we’ve been able to play and in that time I haven’t had clue one about the area the players are heading to next, so I decided to give them a stake in the worldbuilding and tell a story about the founding of that town, several hundred years in the past. I’m not sure how it’s going to go, though. It almost seems like too big of a gimmick that the players will see right through, but they have all been clamoring to try new classes and races for a while. Ideally, this’ll provide some historic figures for my world as well as some continuity (and sites worth visiting) when they actually get to the town with the original party. I figure in the worst case, it’ll be a couple sessions of unmemorable fights and events and I’ll give the main party some exp to make up for the wasted time, but if it goes well, it could be a regular thing, with the players learning about the history of the world through the eyes of the heroes of the past. Also, if any of them die, the A Party might find some really nice gear in a few sessions. 🙂
newbiedm
May 11, 2009
Very cool, going back in time… i may try that…
Jesse
May 22, 2009
My group has three DMs, so we’re dealing with players coming and going all the time. We’ve each given our characters a story reason to sit out a adventure. For instance, my character is an assassin, who adventures to improve his rep, allowing him into more social circles. So when the current adventure is over, my character will go off on an assignment, and the current DM (who’s character was researching a clue we’d found) will rejoin the party. So far it’s worked extremely well.