She did well, actually. She reached the age of child, and moved into an apartment between the kitchens and the hospital that had belonged to a noble until I'd made him a better suite of rooms in the bedroom levels. She liked the statues in it, and I allowed a few other children to migrate to the fort, so she had company her own age. They would play chasings in and out of the aquifer-fed kitchen waterfalls.
At around her age of five, the caverns were hit by multiple Forgotten Beasts. I did my best to wall them up, and we survived for a few months, while I watched those brave dorfs who had been walled in with the beasts do their best to survive. One of the beasts turned out to be firey, and the fps was shot to hell. I played for as long as I could, but when a werebeast arrived, all hell broke loose. With horridly bad fps, I did my best to wall in the victims of the werebeast attack, and the children were locked in a suite of "saferooms" with food and a well. Things went from bad to worse, and I eventually saved and stored the fort as a sad monument to what can happen if you don't have a good Forgotten Beast Plan made before you breach the caverns.
She's still alive, I guess, and about six years old. I just haven't loaded up that fort, as I'm not sure how I could do anything which won't lead to the inevitable...