The Cahill family is divided into twelve branches, each named after a specific constellation:
* The Madisons (Ursa Major)
* The Tollivers (Ursa Minor)
* The Ekaterinases (Orion)
* The Kazakovs (Gemini)
* The Styles (Taurus)
* The Vespers (Andromeda)
* The Palladinos (Leo)
* The Albans (Aquarius)
* The Morgans (Sagittarius)
* The Ivans (Cancer)
* The Cabots (Virgo)
* The Bagshaws (Scorpio)
Amy and Dan are descendants of the original Cahill founder and represent the entire family in the story, as they are the only ones who aren't tied to a specific branch. This makes them unique and allows them to learn about the history and secrets of all twelve branches.
