"Why, you'll be 'changed, m'dear. We'll swap you for a human child who'll make a good servant to the band. Half-humans never work out 'mongst the Folk. No, Never do."
"But-I'm half Folk too!" Moql swallowed hard, trying to swallow the inescapable next thought. "What if -I never work out -'mongst the humans?"
The Prince, musing, seemed not to hear the question.
"Aye, you're neither one thing nor quite yet t'other," he agreed. "Pity, but there 'tis."
The Moorchild is a story about a changeling girl (Moql/Saaski), abandoned by the Moorfolk (read: Fair Folk) for being half human, who never quite fits into human society because of her eldritch nature. Her human parents are ridiculed for her strangeness by the intolerant villagers, but take it in stride and do their best to provide for her. She often runs off to play on the Moor, the only place where she feels at peace.
- Arcadia: The village Torskaal.
- Becoming the Mask: Saaski manages to make herself forget her past life in the Mound almost entirely.
- Bigger on the Inside: The Mound.
- Dark-Skinned Blond: The Folk are a species of Dark Skinned Blonds; Saaski inherits the appearance, which becomes a point of vicious teasing.
- Deadly Decadent Court: The Mound seems like this to humans because of the Folks' glamour. Applying Folkish ointment to the eyes fixes this, however.
- The Ditz: Most of the younger Moorfolk, and plenty of the adults. Most notable is Tinkwa; he promised to help Saaski and Tam out of the Mound, but when he vanished, Saaski shrugged and assumed that he had forgotten.
- The Fair Folk: The Moorfolk. They kidnap children and replace them with their injured, elderly, and misbegotten, they play pranks and steal from humans, and they have no concept of love, hate, or empathy.
- Funetik Aksent: The Moorchild features a toned down but clearly Scottish dialect, being set in Scotland.
- Glamour Failure: Many, many times.
- Moql gets found out to be half human after an Epic Glamour Fail.
- While out on the Moor for a picnic, Saaski saw one of the folk stealing bits of her friend Tam's lunch. She laughs and asks Tam why he let the little man steal it. Tam looks to where she's pointing and says there isn't anything there.
- When Saaski and Tam break into the Mound to get Saaski's parents' real daughter back, Tam sees everything as being all fancy. When Saaski puts special ointment on one of his eyes, he can see things as they truly are out of that eye, but only if he closes his "lying eye".
- When out and about, the Moorfolk have a thing for slapping runes on everything they see. Why not? It's not like anyone is going to be able to see or read them.
- Half-Human Hybrid: Saaski is the misbegotten daughter of a pretty Folk girl named Talabar and a Fisherman whose name nobody in the Mound remembers.
- Heel Face Turn: From Saaski's point of view, Old Bess. As a baby, she retains enough Folk survival instinct to view Old Bess as an enemy who wanted to kill her, even after she forgets about her life as Moql. As she grows up, though, Old Bess becomes a mentor to her and the first person she goes to when she remembers being half Folk.
- Kaleidoscope Eyes: Saaski has eyes that change color depending on her moods, a telltale sign that she is actually a changeling.
- Kids Are Cruel: The other children pick on Saaski because she's "eldritch" and "freaky-odd", and their teasing often turns violent. When a prank could have turned deadly (an older, stronger boy tries to push her in a deep pond), nobody helps her.
- And later in the book, they practically beat her for trying to join in a game.
- Little People: Intersects with the Fair Folk to create the Moorfolk.
- Loners Are Freaks: Saaski. Also her grandmother, Old Bess.
- Lonely Together: Saaski and Tam. Saaski because the villagers are scared of her, and Tam because he's an orphaned goatherd.
- Magic Music: Subverted. Saaski's bagpipe playing is at first believed to be this, but the villagers soon realize that the music has no magical properties, it's just strange.
- Meaningful Name: Technically, unmeaningful name; Saaski remarks that Anwara's baby wasn't given a real name - simply "lekka", the Moorfolk's word for "stolen".
- Moorfolk Don't Cry: When Moql learns she's to be banished from the Mound, she begins to cry. Pittittiskin remarks, "Crybabying, eh? That's a human trick, it is."
- Narnia Time: "Time runs different in the Mound", the Mound being the home of the Folk. A human who's lured in can stay for what feels like a season or at most a year, and then when kicked out discover that a few decades have passed and he has aged accordingly. Mound time doesn't affect you if you don't have their food or drink.
- No Ontological Inertia: When Moql's biological father leaves the mound, he ages instantly into an old man, because five and fifty years have passed in the normal world where only a season has passed in the Mound.
- Used again in reverse with Yanno and Anwara's real daughter, who de-ages upon leaving the Mound.
- Not So Different: What Old Bess comes to realize about herself and Saaski.
- So What Do We Do Now?: She decides to go with Tam to the King's Town to play her pipes on the street, since she can't go back to Torskaal or the Mound.
- Strange Girl: Saaski, as well as Old Bess in her youth.
- Stranger in a Familiar Land: When Saaski returns to the Mound with Tam on their rescue mission.
- Torches and Pitchforks: On Midsummer's Eve, the adults of the village go after Saaski with (iron) torches, salt, St. John's Wort, and a cross made of rowan wood. While she survives the mob, they set a deadline of tomorrow evening before they'll return to Burn the Witch.
- Weaksauce Weakness: The Moorfolk, and Saaski by extension, hate Rowan wood, salt, iron, yellow flowers (especially St. John's Wort), and holy water. The iron thing is a huge pain for Saaski because her adoptive father is the local blacksmith, and everything else becomes an issue on Midsummer's Eve, when the villagers weave garlands of yellow flowers and make their kids gather rowan wood for the Midsummer Bonfire.
- What Is This Thing You Call Love?: When Saaski is almost drowned by one of the village kids, her goatherd friend Tam asks, "Don't you just hate them for that?" Saaski replies that she doesn't know what he means by "hate". After a bit of fumbling, he explains that it's the complete and total opposite of "love". This is less than helpful.
- Wild Hair: Another trait Saaski inherited from the Folk. Her hair is described as looking pale and bushy, like a heap of straw.
- Wistful Amnesia: Partially subverted; Saaski occasionally gets the feeling that she's missing something, but usually subconsciously pushes the wistfulness away.
- You Can See Me?: See the picnic example under Glamour Failure. The same Folkish man (Pittitiskin) comes back while Saaski is playing her pipes and asks this. When he asks her which eye she can see him best out of, her Genre Savvy reminds her that whichever eye she says will be struck blind, so she replies "I got eyes in the top of me head, like."
- You Can't Go Home Again: Moql getting kicked out of the mound, or so she thought.
- Again after the townsfolk learn Saaski's true nature. She makes one last stop to drop off the real Saaski, though. She's just as happy Walking the Earth with Tam, as she never quite felt at home in Torskaal anyway.