What is the character?
As Bilbo Baggins put it, adventures are nasty and dreadful things that make you late for dinner. Unfortunately for Mr. Baggins, he didn't get a great deal of say in being pulled along with one. So has the life of the Trapped gone -- she never had any interest in adventure, but circumstances have forced her into one, usually by pulling her along until the only way out of the mess is to see things through to the end. Given the choice, she would prefer to be somewhere far away from all the fighting and struggling.
Sometimes, this might mean the character was previously just a normal person living a normal life. In other circumstances, she might have been consciously avoiding taking a more active step forward -- an officer in Star Trek Online who never wanted a captaincy so much as a research position, for instance. And in still other cases, the Trapped used to be an adventurer but was content to hang up her hat and leave that life in the past. What she used to do matters less than where she is now, and that's quite far from where she wants to be.
What's the angle?
The reason for a Trapped character's being on the road is at once easier and harder than other archetypes' reasons. It's easier because you never have to answer questions about why, say, a Scholar isn't just enrolled at a particularly large university. Trapped characters are being forced on the road without any real choice in the matter. Unfortunately, that means that the reasons your character is adventuring become much more important, since logically, as soon as her problems are solved, she'll bolt back to the quiet life.
Common reasons include a family member in danger or the destruction of one's home -- it's hard to go back to the homestead when it's been razed to the ground. There's also the possibility that the Trapped has some particular power or ability that forces her out of her home, in the sense of the venerable Call of Cthulhu investigators. Other options include a brutal political regime, running from incarceration (just or unjust), debts, or even just getting straight-up shanghaied into a situation that generates enemies faster than you can deal with them. Put enough distance between the Trapped and her home, and she's stuck without a clear path back -- bad for her, but good for roleplaying.
What makes it interesting?
The fact of the matter is that a life of high adventure on the road seems interesting to us as players because, well, we don't have to deal with it. We get to log in and have all the fun parts without dealing with the nitty-gritty mechanics of being hungry or cold or scared or otherwise kept away from the shelter of civilization. Even in games like Star Wars: The Old Republic, where a certain degree of civilization is almost ubiquitous, there's a lot more security in staying at home instead of heading off into the black and facing countless perils. The Trapped represents a viewpoint that needs to be represented, the everyman role, the person who says that she would much rather be safe and warm than out shooting monsters.
If you run a Trapped character long enough, you have the added benefit of having a character who can properly react to the variety of changes taking place in the game world. Usually, players are clamoring to enter each new area of the game as it's added. But if your character doesn't want to be on the road in the first place, she's the one going against the tide and trying to stick with the safe and familiar. If you can't go home again, you can at least not leave whatever passes for home at the moment.
What should I keep in mind?
Trapped characters are going to walk a narrow line between "periodic complaints" and "whining." Yes, it's entirely within reason to have the character state that she would rather be back at home, especially during particularly nasty stretches. Bring it up too often, however, and you're effectively removing the fun of being in a fantasy world with all of the nagging and consideration of real life. Mix some enjoyment into the equation, too, some moments where the Trapped winds up enjoying herself despite everything.
Much like you would with a Rogue, you're also going to need to give this character a good reason not to up and run. Unlike a Rogue, the Trapped is deeply loyal, and that will generally stretch pretty far, but it won't quite cover everything. Keep your character tied down with other people or you're going to be left with someone who by all rights shouldn't be sticking around.
For those who have missed the previous archetype columns:
As always, I'm eager to hear what you think, either by mail to firstname.lastname@example.org
or in the comments field. I mentioned last week that I'm planning to head back to more discussion of long-running storylines, so that's on deck for next week.
Every Friday, Eliot Lefebvre fills a column up with excellent advice on investing money, writing award-winning novels, and being elected to public office. Then he removes all of that, and you're left with Storyboard, which focuses on roleplaying in MMOs. It won't help you get elected, but it will help you pretend you did.