A couple weeks ago, playing as a PC again in my friend Erik’s Underdark campaign, my party came across three thralls kept by a mind flayer. One of them turned out to be my character’s brother, so while one might normally think very carefully before trying to separate a mind flayer from his possessions, the choice here was obvious.

We fought the mind flayer and we were swiftly victorious, blowing all of our most powerful abilities as quickly as we could. My character, Elizabeth, saw to her brother’s safety, while the rest of the party decided on what to do with the other two freed thralls. One of them, a half-orc, we had encountered before, and while he wasn’t exactly hostile then, I would have characterized him as “antagonistic.” The other thrall was someone we hadn’t met before, an elf, whom the party decided to bring with us, leaving the half-orc behind.

Now, as a player, it’s gnawing at me that we left that half-orc behind, probably to be taken as a slave again by the mind flayers. (Elizabeth doesn’t much care too much, since she’s busy seeing to her brother.) But as a frequent DM, I can’t help but speculate at the other side of the screen, and wonder whether Erik had plans for that half-orc NPC. We come again upon one of the struggles of collaborative storytelling.

I give Erik enough credit that he either anticipated the possibility that we would leave either or both of the freed thralls behind (or would kill them when they went to defend the mind flayer), or that he has since adjusted his plans accordingly. So I’m not worried. But I wonder how, as a DM, I could ensure that an important NPC, for whom I have Big Plans™, will survive and perhaps even be accepted by my players as an ally. There’s two basic ways to do something like this: create credible inevitability; or trust your players to follow your breadcrumbs.

The latter is (to me) the less interesting of the two. It’s pretty easy to pull off if you have friendly players, but it has the drawback of encouraging meta-game thinking. A shrewd player can pick up on the story arc that you’re building, and understands what’s dramatically appropriate. As long as you’re meeting those expectations of a typical story or adventure challenge dynamic, they’ll play with those assumptions in mind. So when there’s a big scary door that’s definitely trapped and definitely has something evil behind ready to try to eat the PCs, the players are going to expect that there’s some reward, and they aren’t just going to say, “Nah, too dangerous. Let’s go home.” That door is a breadcrumb, and the DM expects the players to follow its trail. Likewise, NPCs with names (especially the ones that you rescue in dungeons) often end up being important in some way, so keeping tabs on them isn’t a bad idea. Of course, my party chose to let this one go.

Then there’s credible inevitability. When Elizabeth saw her brother enslaved by the mind flayer, there weren’t any other options beside saving him. Erik could reasonably anticipate that I would do whatever I could (or whatever my character could) to rescue this NPC. The situation was credible, and the actions I took were inevitable given that situation. This risks railroading if it’s done too heavy-handed, and if it ultimately takes the players in directions they don’t want to go.

Creating that credibility and that sense of inevitability is an art. In Elizabeth’s case, it was easy, because I had made it pretty clear to Erik how important her family was to her. Most times, the DM has to guess to some degree at the decisions his players would make. Some onus lies with the players to create well-defined characters whose decisions are somewhat more reliable than their dice, but some players also just like playing erratic characters.

There’s no single best way to do this; everyone has to give a little bit. The players should try not to be jerks and constantly make left turns; the DM should try to make the path she sets for the players one that they’ll enjoy walking down; she should also be willing to adjust when they don’t like it; and the players should understand that the DM has a story that they have some interest in telling, and should be, while not a slave to it, at least sensitive to it.

Postscriptum: In that final paragraph, I realized I had at first unthinkingly used the “he” to refer back to my abstract DM. I have more purposefully now changed it to “she,” a default I remember seeing often in the D&D 3.x rulebooks. It stood out to me, and I wonder whether my self-edit has stood out to anyone reading this as well.