The Order of Secrets
Homunculi are typically artificial humans with limited independence and intelligence. Many of the order of secrets work with them as a means of creating ‘machine’ artificial intelligence or at least attempting to create such.
The threats of the Shadow Lands however have been using them for ages to replace humans they have killed or taken, which is why so many stories of children who were replaced exist. These try to mimic the personality they replace, but aren’t quite capable of doing so. In the ancient stories they took young children as they were much easier to mimic than adults or even older children.