Eff Rothmer was born a thirteenth child. Her twin brother, Lan, is the seventh son of a seventh son. This means he's supposed to possess amazing talent — and she's supposed to bring only bad things to her family and her town. Undeterred, her family moves to the frontier, where her father will be a professor of magic at a school perilously close to the magical divide that separates settlers from the beasts of the wild.
This book provides examples of:
- The Ace: Invoked in-universe by people who assume Lan is one, thanks to his birth order.
- Adults Are Useless: Averted. The adults are the people Eff, Lan, and William go to with concerns — for good reason.
- Age Cut: Happens a few times, with Eff going through a few years in just a paragraph and then resuming the narrative.
- All of the Other Reindeer: Eff's aunts, uncles and cousins treat Eff like this as she's the thirteenth child.
- Alternate History: The nineteenth-century American frontier, with magic, dragons and woolly mammoths.
- Always Chaotic Evil: Thirteenth children, according to Eff's aunts and uncles.
- Apologizes a Lot: Eff, as a result of the bullying she received as a kid, tends to assume everything is her fault.
- Arbitrary Skepticism: Professor Rothmer thinks Eff's aborted attempt to blow up her uncle was a fluke, even though he's presumably seen stranger things from his students.
- As You Know: Eff starts the book by mentioning how everyone knows seventh sons are special.
- Audience Murmurs: How the Rationalists in Oak River showed their approval of Eff being willing to go out without protection spells.
- Badass Longcoat: Seemingly a requirement for living west of the Great Barrier Spell.
- Because Destiny Says So: Eff spent years being sure that she was going to go bad one day.
- Berserk Button: Don't pick on Eff when Lan is around. Or any of her other siblings, for that matter.
- Boarding School: Lan and William go off to one in the East.
- Born Lucky: Professor Rothmer and Lan are both considered to be this, being a seventh son and a double-seventh son, respectively.
- Bratty Teenage Daughter: Rennie is this for a long time.
- Break the Cutie: Eff's extended family tries to do this to her the first five years of Eff's life. It's part of what convinces the Rothmer parents to move west.
- Bullying the Dragon: Eff's aunts, uncles and cousins spend the first five years of Eff's life bullying her, even while they believe she's a Tyke Bomb who should have been killed at birth and is doomed to become a Big Bad in the future.
- Can't Get Away with Nuthin': Poor Eff can't even get away with things she didn't do!
- Child Prodigy: Lan is treated as one, being a double-seventh child, to the extent that his grandfather hires him a special tutor.
- Children Are Innocent: Examined. Eff is treated as a monster by her extended family for the first five years of her life, despite never doing anything to deserve it. Years later, when she catches herself wondering whether her sister's possible death would change her status as an unlucky thirteenth, her first reaction is to believe that her aunts and uncles were right about her all along.
- Close-Knit Community: Mill City, as they are assured as soon as they arrive.
- Containment Field: The Great Barrier Spell is this, writ large.
- Cool Teacher: Miss Ochiba the magic teacher. She offers lessons in non-Avrupan-style magic, treats Eff no differently upon finding out she is a thirteenth child, and can stop a young mammoth in its tracks. Eff breaks down crying when Miss Ochiba is fired.
- Cub Cues Protective Parent: In-universe, Wash cites it as his rule of thumb when in the settlement territory.
- Determined Homesteader: As the story is about Westward Expansion, it should come as no surprise that several of these show up, including Brant and the rest of the Rationalists.
- Didn't Think This Through:
- If you are an adult bullying a child who has loving parents and siblings, they will show no sympathy when the child hits a Rage Breaking Point, especially when it's supposed to be a happy occasion.
- Rennie admits this to Eff in a private moment after Eff calls her out for disrupting Diane's big wedding day and leaving Eff to take the usual scapegoating. She didn't mean to run away with Brant; it was that the idea of Rationalism was romantic and full of freedom. Rennie also knew that her parents wouldn't be pleased that she got pregnant out of wedlock and didn't consider that the scandal would overwhelm the happiness about Diane's wedding. It's also lonely on the frontier.
- Don't Split Us Up: An unusual example, as it was only for the month or so that the family stayed in their old hometown, but Lan insists that he and Eff stay together so he can protect her.
- Doom Magnet: Eff thinks she's this, among other things, thanks to her extended family's abuse. Her family tells her that it's nonsense.
- Elopement: Rennie and Brant elope after Rennie gets pregnant out of wedlock.
- Energy Absorption: The mirror beetles. The first two parts of their lifestyle seems perfectly normal. However, the adults are drawn to sources of magic, where they use it to trigger their last transformation into the mirrored beetle.
- Enfant Terrible: Another thing the extended Rothmer family suspects Eff of having been.
- Ethnic Magician: Miss Ochiba and Wash, who use Aphrikan (a.k.a. African) conjure magic rather than the Avrupan (a.k.a. European) magic of almost everyone else.
- Evil Uncle: Earn, Eff's uncle who tried to convince Eff's parents to murder Eff as a baby due to her being the thirteenth child. Earn then spends the next five years abusing Eff and encouraging his children to bully her. It's capped off with Earn trying to have Eff arrested at the age of five. Luckily, the Rothmers move West, at least until the wedding. When Eff finally hits her Rage Breaking Point, her family has No Sympathy for Uncle Earn, telling him he deserved it for bullying a child.
- Expospeak: The professors do this occasionally. William and Lan get in on it too, after they go East for school.
- Family Disunion: Diane's wedding goes well... at first. Then Earn gets drunk and decides to take it out on Eff.
- Fantastic Time Management: Quick-drying spells, speed-travel spells, and more.
- Fantasy Counterpart Culture: Played with. As the setting is an alternate-universe Earth, the lands and cultures are pretty much the same, but they all have different names. Columbia is America, Aphrika is Africa, Avrupa is Europe, Ashia is Asia and Cathay is China, among others.
- Flat-Earth Atheist: The Rationalists, to some extent, though instead of not believing in something that's there, they decide to go without it (meaning going about their lives on the frontier without the use of magic to protect them).
- Friendly Rivalry: Lan and William have one going when they come back from boarding school.
- Freudian Trio: Eff, Lan, and William are ego, id and superego, respectively.
- Gentleman Adventurer: Wash is an interesting variant of this, as is Dr. McNeil.
- Good Parents: Daniel and Sara Rothmer, who refuse to treat Eff poorly despite her being a thirteenth child. When Earn keeps trying, they tell him to shut up.
- Guilt Complex: Eff, as she was told repeatedly during the first years of her life that she was inherently awful due to her birth order.
- Harmful to Minors: The extended Rothmer family, ranging from bullying to abuse to telling Eff's parents they should have killed Eff as a baby.
- Hannibal Lecture: Uncle Earn tries to give one to Eff. It doesn't end well.
- Head-in-the-Sand Management: The Settlement Office, particularly under Mr. Harrison.
- Held Back in School: Eff after having rheumatic fever.
- Heroic Safe Mode: Caused by Professor Rothmer with a magic-dampening spell after Eff's argument with Earn.
- Higher Education Is for Women: According to settlers, at least.
- Historical Domain Character: Ben Franklin was a double-seventh son in this world. He and Thomas Jefferson, also a double-seven (something neither was in our world — they were a tenth and an only son, respectively), created the Great Barrier Spell to keep the United States of Columbia safe from Western wildlife.
- I Just Want to Be Normal: Eff, who wishes she was anything but a thirteenth child, and even thinks about joining a Rationalist group where she can't use her magic.
- Inept Mage: Eff, after the incident with Uncle Earn. While she knows the theory behind different spells and can do the setup, when she tries to actually cast them, things tend to go wrong.
- Intergenerational Friendship: Eff with Wash and Professor Jeffries.
- Istanbul (Not Constantinople): Columbia is America, Gaul is France, Cathay is China, and so on.
- Just Think of the Potential!: Brant, about a successful Rationalist settlement opening the rest of the West to settlement.
- Kids Are Cruel: Eff's cousins tormented her when they were children.
- Last Fertile Region: Oak River, due to its lack of magic.
- Magical Seventh Son: Lan. It isn't until the third book that people realize that Eff, as the seventh daughter of a seventh son, also applies.
- Magic Versus Science: Averted. Magic is treated as a science.
- Mama Bear: Mrs. Rothmer, who refuses to let Earn insult Eff, and makes sure to tell him off for calling on the police to arrest a 5-year-old.
- Massively Numbered Siblings: Eff has seven brothers and six sisters. Her father has six brothers and several sisters.
- Missing Mom: William's mother is an invalid, never shows up in the story, and is implied to have no role in rearing her son.
- Muggles Do It Better: Rationalist engineers. Also Brant on the McNeil Expedition.
- My Secret Pregnancy: Eff realizes later that this is why Rennie and Brant eloped.
- No Plans, No Prototype, No Backup: Played with. Jefferson and Franklin did leave behind their notes for the Great Barrier Spell, but since Franklin was self-taught and Jefferson tended to assume that everyone was as well-read as he was, nobody can make any sense out of them.
- Numerological Motif: Seven and thirteen.
- Obstructive Bureaucrat: Mr. Harrison, to the point where Washington got enough complaints to fire him at the end of the series.
- Our Dragons Are Different: They produce steam, for one thing.
- Overshadowed by Awesome: Eff, who's the twin of a Magical Seventh Son.
- Parents Know Their Children: Daniel and Sara Rothmer do, at least. Professor Graham, however, does not.
- The Professor: Several, with Eff's father being the main example,
- Reasonable Authority Figure: Eff's parents and mentors. Her parents refuse to believe that she is bad luck and do all they can to assure her that she is loved and wanted. When Rennie elopes, her parents are disappointed, but her father makes sure to visit Rennie after she has a baby and check that she's all right. Meanwhile, her teachers see her potential and do their best to encourage it.
- Screw Destiny: Not Eff's response, as she's internalized her thirteenth-ness, but the people she reveals her Dark Secret too have a tendency to respond this way. For example, Miss Ochiba responds by teaching Eff about numerology in other cultures, where the number thirteen is not considered unlucky.
- Settling the Frontier: The story features Manifest Destiny and people heading west.
- She Is All Grown Up: Eff puts her hair up and starts wearing longer skirts when William and Lan are back East at college. When they get back, William has this response.
- Shotgun Wedding: It's revealed that Rennie ran off with a Rationalist because she was sleeping with him and found out she was pregnant. Rather than being forced to confess to her family, she ran off.
- Silver Has Mystic Powers: As does sulfur and other minerals and metals.
- Slave Liberation: How Miss Ochiba's parents met. Miss Ochiba's father purchased slaves for a type two liberation, and Miss Ochiba's mother was one of them.
- Southern-Fried Private: Wash has a Southern drawl, and like many other black men, fought for the North in the Secession War.
- Spanner in the Works: Allie is this for Rennie's plan to run away with Brant
- Stern Teacher: Miss Ochiba. On the first day of school, she explains that she wants silence as soon as the bell rings. She enforces this on the first day by magically taking away all sound, including people shifting in their seats, the scraping of chalk, people talking...
- Supernatural Sensitivity: Aphrikan world-sensing can lead to this.
- Synchronized Swarming: Swarming Weasels.
- Terminally Dependent Society: The Rationalists believe society is too dependent on magic.
- Textile Work Is Feminine: The Rothmer women are in charge of laundry and mending clothes.
- 13 Is Unlucky: Why Eff's extended family dislikes her being a thirteenth child.
- Too Dumb to Live:
- Mr. Harrison, who insists on traveling beyond the barrier in an unsuitable buggy, tries to convince the people he's traveling with to use magic on Rationalist land, and he spends the time he's in the Rationalist settlement insulting everyone until they kick him out.
- Uncle Earn, who believes that Eff is a future Big Bad who should have been killed at birth... and handles this by bullying her.
- Twin Desynch: Happens a bit after Eff spent a year bedridden.
- Twin Telepathy: Averted, as Eff and Lan explicitly do not have twin telepathy. However, William later invokes this trope to "explain" why Eff knows that there's trouble where Lan is.
- Unequal Rites: Avrupan mages are called magicians, while Aphrikan mages are called conjurefolk and leaders of Hijero-Cathayan covens are called adepts.
- The Unfavorite: While Eff isn't one of these to her immediate family, she's considered one by her extended family due to being the thirteenth child.
- Unlikely Hero: Eff, the titular thirteenth child. Especially when compared to her brother.
- Unstoppable Rage: Eff fears this is what her magic will become.
- Wide-Eyed Idealist: Professor Rothmer considers Brant to be this to some extent, and even says so in-universe, when speaking to Rennie.
- The Wild West
- With Great Power Comes Great Responsibility: The Rothmer parents view Lan's double seven status this way, stating that their plan is to raise him to be responsible before raising him to be a great magician.
- You Know What They Say About X...: You know what they say about seventh sons, double-seventh sons, and thirteenth children.
- Youngest Child Wins: Subverted. Lan is supposed to be the great magician of the family, but Eff is the one that saves the day.
