Here is a concise summary of the text:
**The Founding of Ilvermorny School**
* Isolt Sayre, a pure-blood witch, is born to a family descended from Salazar Slytherin (Hogwarts founder) and Morrigan (Irish witch).
* After her parents' murder by her aunt Gormlaith (a dark magic user), Isolt is held captive for 12 years.
* Escaping at 17, Isolt flees to America (aboard the Mayflower in 1620) and assumes a male disguise.
* In the American wilderness, she befriends a Pukwudgie creature (named William) and encounters various magical beings.
* Isolt saves two young boys (Chadwick and Webster) from a Hidebehind, discovering they are magical.
* As she nurses them back to health, she meets a No-Maj (non-magical person) named James, who had befriended the boys' family.
* These events set the stage for the founding of Ilvermorny School of Witchcraft and Wizardry, the American counterpart to Hogwarts.
Here are the key facts extracted from the text, numbered and in short sentences:
**Family and Heritage**
1. Isolt Sayre was born to two pure-blood wizarding families.
2. One of her family lines was the Gaunt family, direct descendants of Salazar Slytherin.
3. Her father, William Sayre, was a descendant of the Irish witch Morrigan, an Animagus.
**Early Life and Captivity**
4. Isolt's parents were killed in an attack on their home when she was five.
5. She was pulled from the fire by her aunt, Gormlaith Gaunt, who then raised her.
6. Gormlaith was responsible for the murder of Isolt's parents.
7. Isolt was held captive by her aunt for 12 years, during which she was mistreated and denied a wand.
**Escape and Travel**
8. At 11, Isolt received a Hogwarts letter, but her aunt refused to let her attend.
9. Isolt escaped from her aunt at the age of 17 by stealing her wand.
10. She fled to England, then to America on the Mayflower in 1620, disguised as a Muggle boy named Elias Story.
**Life in America**
11. Isolt arrived in America and vanished into the surrounding mountains.
12. She met two magical creatures: a Hidebehind and a Pukwudgie, which she named William.
13. William, the Pukwudgie, became bound to serve Isolt after she saved his life.
14. Isolt developed a friendship with William, despite his initial ingratitude.
**Encounters and Events**
15. Isolt understood the language of a Great Horned River Serpent, due to her descent from Salazar Slytherin.
16. The serpent told her, "Until I am a part of your family, your family is doomed."
17. Isolt and William encountered a horrific scene: two dead adults and two injured boys, attacked by a Hidebehind.
18. They destroyed the Hidebehind and saved the boys, Chadwick and Webster.
19. The boys, once recovered, proved to be magical.
20. Isolt met a young No-Maj (non-magical person) named James, who had befriended the Boot family (the boys' family).
**Founding of Ilvermorny (implied, not directly stated in these facts, but setup by them)**
*Note: The actual founding of Ilvermorny School of Witchcraft and Wizardry is not explicitly detailed in the provided text, but these facts set the stage for Isolt's future actions, which likely include establishing the school.*