Chapter Summaries

Gavin gave Snape the Biphasic Transformation Potion formula, then comforted Cordelia and spent the night with her in the Room of Requirement. At breakfast, he learned that Saul Croaker had invited him to the Department of Mysteries, and Dumbledore asked what he thought of the invitation.

• Gavin shared the Biphasic Transformation Potion formula with Snape, who became absorbed in studying it, and Gavin left after teasing him about brewing it himself.
• Cordelia waited for Gavin outside Snape’s office, admitted she feared he might disappear again, and asked him to stay with her; Gavin joined the beds and let her hold him through the night.
• Gavin arrived at breakfast exhausted while Hogwarts students spread wild rumors about Malfoy, and Fred and George mocked Malfoy until he lost his temper.
• Gavin asked Ernie about his grandfather’s restorative potion research and realized he could use his junior Philosopher’s Stone to help; Professor McGonagall then summoned him to Dumbledore’s office.
• Dumbledore showed Gavin a black-sealed letter from Saul Croaker inviting him to visit the Department of Mysteries.

Gavin agreed to wait until Christmas for Dumbledore to return the charged Philosopher’s Stone ring, on condition that he attend classes and avoid incidents, and Dumbledore made him Lupin’s Defense Against the Dark Arts teaching assistant. Gavin then helped Harry practice the Patronus Charm, ending the lesson by suggesting they catch a real Dementor for practice.

• Dumbledore told Gavin that Saul Croaker wanted to meet him at the Department of Mysteries, but the visit would have to wait while the department repaired damage from Dumbledore’s earlier search for Gavin.
• Phineas Black claimed that Dumbledore had devastated the Department of Mysteries after an Unspeakable insulted him, while Dumbledore dismissed the account as exaggerated.
• Dumbledore said he had blocked Lucius Malfoy’s motion to expel Gavin, partly because Alaric Rowle and other governors opposed it after Draco’s fake injury was exposed.
• Gavin asked for the charged ring to research the Elixir of Life for Cordelia; Dumbledore refused until Christmas, when he would give it to Gavin if Gavin attended classes and caused no incidents.
• Dumbledore appointed Gavin as Lupin’s teaching assistant, and Gavin spent the afternoon distributing handouts, assisting in class, and moving the Boggart’s wardrobe.
• Harry produced a sustained cloud of silver-white mist with the Patronus Charm, and Gavin suggested catching a real Dementor so Harry could practice against one.

Gavin took Harry and Lupin to retrieve a Dementor for Harry’s Patronus practice, then coached Harry through facing it until he produced genuine silver mist. After leaving the classroom at six, Gavin went to Snape’s office for his usual evening work and discovered Snape was writing a study about awakening a latent female personality.

• Gavin persuaded Lupin to bring a Dementor from the Black Lake as a teaching aid and led Cordelia, Harry, and Lupin to collect Number 78.
• Gavin forced the reluctant Dementor to cooperate, stored it in an enchanted bag, and brought it to the classroom for Harry’s practice.
• Number 78’s chill overwhelmed Harry at first, but Gavin guided him to imagine the people and moments he wanted to protect.
• Harry blasted Number 78 with an unusually powerful red Disarming Charm, then successfully cast the Patronus Charm and produced silver mist.
• Gavin left Harry to help Lupin put away the Boggart wardrobe when his shift ended, then went to Snape’s office to clean Flobberworms.
• Gavin read the title of Snape’s parchment, which described a study of extending a potion’s effects to permanent Transfiguration and awakening a latent female personality.

Gavin secretly learned Snape’s painless improvements to the Biphasic Transformation Potion, then struggled to find a way to cultivate his white magic while his Obscurus absorbed its overflow. Cordelia used the potion to turn Gavin into a girl, while a scarred wizard learned that Newt Scamander’s grandson was at Hogwarts and began plotting to capture him.

• Gavin used a wandless Super-Sensory Charm to read Snape’s notes and learned the painless method for reshaping the Biphasic Transformation Potion.
• Snape caught Gavin reading his notes, threw him out, and considered giving his detention to Lupin before studying the Crystal Bottle’s pale blue potion.
• Gavin brewed the improved potion and realized his Obscurus absorbed the excess magic he needed to cultivate his white whirlpool.
• Cordelia confronted Gavin about the password and beds, then seized a bottle of potion and tried to make him drink it so he would become a girl.
• A scarred wizard learned that thirty-seven rivals had vanished after traveling to Britain and that Newt Scamander’s grandson was at Hogwarts, then decided to capture him.

After discovering that his female body doubled his magical capacity and let him seal the Obscurus, Gavin chose to keep using the Biphasic Transformation Potion to cultivate higher-level Magic. He disguised himself as a boy at Hogwarts, but his female pheromones unsettled his roommates, while Tracy took Cordelia away to make her sleep in the Slytherin dormitory.

• Cordelia teased Gavin after he emerged from the Room of Requirement as a girl, then reassured him that she would search for her missing family someday, with his help.
• Gavin discovered that his female form widened his Alaya Consciousness River and let him seal the black Whirlpool with a charm supported by different-source Magic, allowing the white Whirlpool to condense when his body changed back.
• Gavin decided to keep taking the potion to cultivate Magic, drank another dose, and used Human Transfiguration to disguise his female form as his usual boyish self.
• At breakfast, Tracy Davis accused Cordelia of neglecting her dormitory bed and insisted she sleep with her that night; Gavin welcomed the chance to sleep alone while Cordelia warned his roommates not to bully him.
• Gavin realized his pheromones were making Justin, Rolf, and Ernie act strangely, then returned to the boys' dormitory after further experiments; his three roommates stayed awake and restless while he slept peacefully.

Justin, Rolf, and Ernie blamed their sleepless night and strange attentiveness to Gavin on “beauty genes,” while Gavin reassured Cordelia and received news that Hufflepuff would face a better-equipped Gryffindor first. After promising Cedric help, Gavin brought a battered Cleansweep Seven to the team meeting and presented it as his plan.

• Justin, Rolf, and Ernie realized their sleeplessness and unusual behavior had begun after Gavin appeared, and Gavin convinced them they might have inherited “beauty genes.”
• Cordelia confronted the three boys, then relaxed when Gavin explained their behavior; she later read Professor Roscoe’s letter about Gavin’s request for heavy water.
• Cedric told Gavin that the other houses had upgraded their brooms, including Gryffindor’s Firebolt and Ravenclaw’s assembled Nimbus 2000s, and Gavin learned Ravenclaw had used Lucien Vallet’s old manuscript pages.
• Cedric revealed that Hufflepuff’s first match would be against Gryffindor and persuaded Gavin to honor his promise to help the team.
• Cordelia insisted on accompanying Gavin to the Hufflepuff meeting, where the team described how badly their brooms lagged behind their rivals’ equipment.
• Gavin placed a battered Cleansweep Seven on the table and told the team it was his plan.

Gavin tested the Mark 2, a battered Cleansweep Seven fitted with his homemade Icarus Core, and proved it could outrun a Firebolt. He offered to equip all seven Hufflepuff players before their opening match, while the team tried to keep the upgrade secret from the other houses.

• Gavin revealed that he had replaced the Cleansweep Seven's core and named the modified broom Mark 2.
• At the Black Lake, Cedric accidentally launched the Mark 2 at full force and crashed into a tree and ground Gavin had transfigured to cushion him.
• Cedric tested the broom at low power, then raced Gavin's Firebolt at 30% and won by several broom lengths.
• Gavin explained that he had made the core himself after learning from Lucien Vallet, whom he had paid with potato recipes, and that the school budget rules let Hufflepuff value each modified Cleansweep Seven at less than four Galleons.
• Gavin promised one Mark 2 for each Hufflepuff player, and Cedric told the team to collect six more battered Cleansweep Sevens and hide their plan until the opening match.
• The Hufflepuffs worried that Cordelia had overheard their secret, but she said she could not understand them anyway.

Gavin went to Hogsmeade with Cordelia, but the Biphasic Transformation Potion’s realistic effects caused his transformed body to menstruate, ending his disguise and leaving him in severe pain. As Cordelia went to fetch him hot tea and a hot-water bottle, footsteps approached the alley where he waited in a dangerously bad mood.

• Gavin agreed to spend the Hogsmeade weekend with Cordelia after reassuring her that he was willing to waste time with her.
• On Saturday, Gavin used advanced Transfiguration to disguise himself as a boy and went to Hogsmeade with Cordelia.
• After they avoided a Dungbomb cloud, Cordelia questioned how Gavin knew the village’s back streets, and he reassured her that he belonged to her.
• Gavin suffered severe cramps in a secluded alley, and the Transfiguration dissolved to reveal his black-haired girl form.
• Cordelia covered Gavin with her warm Robes and went into a bakery to get him a hot-water bottle and sweetened black tea.
• Gavin reconsidered abandoning the Biphasic Transformation Potion despite its costs, then heard hurried footsteps approaching behind the ivy-covered wall.

Rolf Scamander was ambushed by a Dark Wizard who had discovered he was the Secret Keeper of the Scamander family home, but a mysterious black-haired girl killed the attacker with controlled blue Fiendfyre. The chapter left Rolf stunned by the girl’s power and composure.

• Rolf got lost while avoiding the Weasley Twins’ Dungbomb and found a pale black-haired girl sitting unwell in an alley.
• A scarred Dark Wizard trapped Rolf behind sealing barriers, attacked him, and revealed he had deduced Rolf was the Secret Keeper of the Scamander home.
• Rolf escaped the barrier with a Diricawl feather Amulet, but returned to the alley when he realized the Dark Wizard might harm the girl.
• The Dark Wizard subdued Rolf and threatened the girl, who stood and cast Protego Diabolica.
• The girl’s blue Fiendfyre burned the Dark Wizard to ash while precisely sparing Rolf, and Rolf watched in awe.

Gavin concealed the identity of the dark-haired girl who had saved Rolf from a Dark Wizard by claiming she was his distant cousin, Gu Wen. As Rolf resolved to stay beside Gavin, Sirius left the Shrieking Shack during the Halloween Feast and headed for Gryffindor Tower to kill Peter Pettigrew.

• Cordelia found the dark-haired girl after she burned a Dark Wizard to ashes, treated her cramps, and hurried away with her while the girl secretly took the wizard's tool bag.
• At the Halloween Feast, Rolf told Gavin, Justin, and Ernie about the attack, revealed that the wizard had identified him as his family's Secret Keeper, and explained that Newt had ordered him to stay with Gavin.
• Gavin claimed the mysterious girl was his cousin Gu Wen, and Rolf added her to his appearance ranking while moving Cordelia down to third place.
• Rolf insisted on following Gavin even to the Lavatory, while Harry left the Feast early and Ron and Hermione followed with sweets for him.
• Sirius emerged from the Root Passage beneath the Whomping Willow and set off for Gryffindor Tower, determined to kill Peter.