In Fate: The Winx Saga, Bloom (Abigail Cowen) is a fairy who was raised among humans, without knowledge of the fairy world, or her own fairy power. After her fire powers violently manifest, she travels to Alfea, a magical school in the fairy world, to be with others of her kind and to learn how to control her abilities. She’s initially made to believe she’s a human who is several generations removed from a fairy ancestor, but she’s too powerful for someone who has two human parents. Bloom spends the bulk of the six-episode first season trying to discover the truth of her identity, and in that process, she discovers that she is a Changeling. But what exactly is a changeling? Allow us to explain.
Changelings are fairies who are left in place of a human infant or child that has been abducted by fairies. In [traditional] European folklore, fairies were thought to be responsible for children who fell suddenly ill or who would show symptoms of disorders that weren’t known or understood then (but which we now have names and diagnosis for). People would do all kinds of weird to downright dangerous rituals to test whether their children had been stolen and replaced with a Changeling. They’d sometimes do much worse to cast the fairy out and get their own child back.
But why would powerful, ethereal beings want to take normal, boring human children?
Fairies take and raise human children to be their servants. In some iterations, fairies —fae, faeries, fair folk— have certain cultural customs and restrictions, like the inability to lie, which can be circumvented with human help. A human who knows all the fairy rules but has no compulsion or directive to follow them can be used by fairies for all sorts of nefarious purposes. Also having someone to run errands can’t hurt.
Fairies also make the swap to be mean or enact revenge. Fairies are often depicted as tricksters, and Changelings are one manifestation of that categorization, taken to its extreme.
On a seemingly sweeter note, some fairies swap older or ailing fairies for human babies so the fairy can be loved and cared for by the humans before it dies. Whether that is soft or sinister is up for interpretation, and it’s the storyteller who decides whether Changelings are inherently good or bad.
In Fate, Changelings are taboo. Aisha describes the practice as barbaric, and says it’s something fairies haven’t done for centuries. No further information is given about why Changelings were a thing to begin with, or what changed and why, but inferences can be made. Changelings are bad. The person who leaves infant Bloom in the human world does so knowing it is at minimum, culturally unacceptable, and possibly breaks some laws.
The way kids treat Bloom when they find out she’s a Changeling is similar to the way kids treat Harry Potter when they learn he can speak Parseltongue. Bloom is unfairly regarded with fear or suspicion even though she cannot possibly be responsible for that circumstance. But Bloom couldn’t help being whisked away into the human world as a Changeling no more than Harry Potter could help becoming an horcrux. And if Bloom’s treatment by everyone around her is anything to go on, being a Changeling in this universe is akin to being marked with a lightning bolt scar.