I recently incurred the wrath of the Random Number God, and got an initial two migrant waves totalling up to a mere 7, doubling my fortress' dwarf count, and I was cool with that, a slow start is a steady start... But then they came. A wave of 39 dwarves, mostly children, rangers, and those strange dwarves that only have a meager amount of skill in something strange like wax making.
Well, I said screw that. Unfortunately, I didn't have a drawbridge at my entrance. But I did have a mason. The wall went up and quite a few of the children got in, but I was fine with that, so long as nobody else did. I'm not quite yet skilled enough at DF to handle huge fortresses yet, which is why I set my init file down to a fort population cap of about 25.
My plan was simple. My fortress was now completely separate from the outside world, and it was going to stay that way until the dwarves outside had starved, dehydrated, or tantrumed their way to death. I felt a mild ping of regret when I saw a dwarf with several good social skills out, one I could make my broker and get good deals from merchant caravans. But no remorse; the dwarves outside were sentenced to slow death to preserve the fortress.
And then, another wave. It shot the dwarf count all the way up to 83, and I realized that on upgrading my DF to .34.06, I hadn't remembered to change the init files back down. The task of waiting out all the outside dwarves immediately became significantly harder. I was out of wood, and couldn't send a dwarf outside to chop any trees without unleashing a flood of children into my fortress, who would drain resources faster than I could make them.
Then, dwarves began to die. "Fantastic!" I thought, the third-wavers are beginning to thin out! Alas, this was not the case. I had done something I had not in quite some time. I forgot the booze. The increased dwarf count drained the beer and food supplies faster than before, obviously, and I had completely forgotten about it. In a desperate haste to save the fortress, I pierced a muddy pool and let the dwarves drink from it to keep them alive long enough to get the farming plots up to the job.
Then, of course, the third wave migrants right outside my door streamed in. It wasn't a deep pool, and it had ramps up to the surface. They had a way in, and used it. I sealed it back before more than a few made their way inside, but the damage was done. The fortress population increased, with a bunch of extremely unhappy dwarves added to the populous.
That's when the tantrum spiral started. It went on and on, my only saving grace was a legendary dining room I'd set up extremely early on. As time passed, dwarves got pissed, melancholy, calmed down, and took their own lives. Smack-dab in the middle of the dehydration, tantruming, and chaos during which I only barely managed to keep the general population alive, it happened. A dwarf was found dead, drained of blood.
Of all the things, I now had a vampire to find and deal with; and did. It was that socialite from before, who I burrowed into a bedless, empty room, and locked the door on. That vampire was now my contingency plan. The one, final, last-ditch trump card to keep this fortress alive. Slowly, tantruming grew less frequent, and I had dwarves clean up the place, dumping garbage into the volcano, rebuilding workshops, making sure the crops grew.
And after two years, it finally stopped. The tantrum spiral ended, with what was once 83 dwarves on-site, reduced to a mere 29. The init file changed ahead of time, no more migrant waves are incoming. The fortress can, finally, begin to prosper once again. The Vampire, once a steady rock of not-giving-a-shit about all the death and hate in the fort, went on a mood I couldn't fulfill, and went insane. My two star dwarves, a spearfdwarf and a miner from the initial embark, are still alive. The Fortress remains sealed off from the world, dancing on the brink of death for such a long time, but once again stable. Nobody even knows about the goblin siege outside, nor do they care whether or not there is one.
For now, the fortress goes on. The Village Zustashnazush Zirilmafol Zarut lives to fight another day. Ancientblood, the Fiery Chamber of Insanities, lives up to its name, and will hopefully continue to do so.