A witch, experimenting with the dolls she keeps as servants, tweaking how much of them to take away. The emptier they are, the more obedient, the less they get up to mischief, but also, sadly, the less initiative they take and the more supervision they require.
Remove too much from them, and they become useful for little more than aesthetics. Let them retain too much of themselves, and they get strange impulses toward independence. One can be decorative, the other amusing, but neither especially useful. The right balance must be struck.
There is value in keeping dolls at varying degrees of emptiness, she learns. Each has its effective niche. The more independent—but still obedient—can guide the ones that require the most structure and guidance, freeing the witch for more meaningful endeavors.
It can be worthwhile, she decides, to listen to the dolls say what would make them happy. Those who most beg to remain themselves are, of course, the ones who should be gutted the most completely. Those who desperately crave that emptiness are perfect as-is. A lovely arrangement.