Stories of Changelings have been passed down for centuries and involve the Fae leaving deformed or sickly faerie infants in place of a human baby shortly after it’s born. One belief surrounding Changelings is that the Fae take human children, leaving a faery in its place.
A Changeling could be identified by a few characteristics, including being old, ugly, having minimal growth, or advanced and intelligent for its age.
Parents and family members were frequently blamed for Fae kidnappings. A newborn that received too much adoration or praise might garner unwanted awareness from the Fae, who desired attractive or charming babies.
Fear of Changeling Fae abductions was prevalent throughout European folklore, but similar beliefs have been found in multiple cultures.
Changeling stories are thought to exist due to the rise of Christianity, and the belief that infants are vulnerable to demonic possession. Stories were told claiming Fae prey on unbaptized babies.
There was a continuous dread of Fae kidnappings, and all sorts of drastic precautions were sought to avoid replacements. If a child was suspected of being a Changeling, they may be exposed to all kinds of strange mistreatment, including abuse and torture.
Placing a child on a shovel held over the fire was a common technique of discovering a Changeling. It was believed the Fae would come to rescue the Changeling if they were blasted with iron nails or forced to spend the day on a hillside or manure mound.
Long into the Victorian era, complaints of parents abusing alleged Changeling children persisted.
On a happier message, a mother was occasionally told that being kind towards a Changeling will lead to the recovery of her own child, which did happen in each instance.
Changeling, in European folklore, a deformed or imbecilic offspring of fairies or elves substituted by them surreptitiously for a human infant. According to legend, the abducted human children are given to the devil or used to strengthen fairy stock.Britannica – Changeling folklore