WMG: The Kane Chronicles
Nut and Geb are aspects of Gaia and Ouranos from Heroes of OlympusThey have very different personalities, just as Aries may be a Blood Knight Jerkass while Mars is a reasonable Sergeant Badass. But they both have Earth and Sky being held apart by another power. Given the events of Heroes of Olympus this may have made taking a message between them a case of Nice Job Breaking It, Hero, but it also may give some hope: if they can arrange for the Geb aspect to supplant Gaia, mother earth won't be evil anymore. That would fit better with the ecological message from the previous series.
The Faust family is descended from the Faust.The universe of this series fits All Myths Are True and at least some elements of the Abrahamic religions are shown to be true (Moses defeated the magicians of the House of Life). So it's possible that Mephistopheles exists in the story's universe as well.
In-universe Lauren Faust is a wizard.She is a wizard, but never used any ancient knowledge on her works beyold the point of reference, all her doings such as the creation of My Little Pony: Friendship Is Magic are pure skill.
Related to above, in-universe brony comunity is partially aware of Lauren Faust being a wizard.This is treated mostly as a meme by the comunity and no one actually takes it serious, however, the few bronies who too are wizards have a deep respect for her.
The books' titles relate to their endings.
- The Red Pyramid has Set on the loose with Apophis on the rise, while The Throne of Fire ends with a weak Ra and a preparing-to-escape Apophis, and soon there'll be The Serpent's Shadow.
- Now, in Egypt red is a color of chaos while black is a color of order. So the first two books with their cliffhanger endings have titles that evoke that color (Red is red, and fire is usually depicted as red) while the third one evokes the color black (shadow- black). This hints at an orderly, happy ending to the trilogy.
There will be a three-way crossover with The Kane Chronicles, the Percy Jackson series, and Rick Riordan's future series based on Norse mythology.
- They're all in the same universe, and it's implied that it will happen at the end of The Serpent's Shadow. Plus, it would be awesome.
- Further WMG: other mythologies will also appear, although not to the same degree.
- As of the short story "The Son of Sobek" Percy and Carter have actually met, and Percy now has a hieroglyph on his hand that will summon Carter if a need arises. Carter is dreading that day.
The Egyptian God of Ice will be discovered in the above-mentioned Massive Multiplayer Crossover.
- Either that or Felix will figure out a way to channel one of the other pantheon's gods, possibly the Norse, since those gods are the only known pantheon to have an Ice Deity.
- He'll be the first magician to follow the path of Skadi.
The recordings themselves will play a role in the crossover.The second book makes it quite clear that the Kane Chronicles are being published in-universe. While the Literary Agent Hypothesis is nothing new, it would be a good way to unite the two casts, so at least one of the demigods will have read them. Nico's a likely candidate - he's nerdy enough, and he'd certainly be interested in Egyptian mythology.
- And Rick Riordan himself will appear as a character, along the lines of Clive Cussler showing up in some of his novels.
Felix will be the main character of a Sequel Series
- It's implied several times that he's exceptionally powerful but he never really gets a chance to show what he can do. In a sequel, not necessarily the crossover, he could be the one with the power and wit to hunt down Setne.
- Or, according to a Headscratcher theory about Riordan making a Norse series, Felix could be channeling a Norse god, Since Egypt doesn't HAVE an ice deity while the Norse do: Skadi.
Felix will take over the Antarctic NomeAnd given access to all that ice and all those penguins, he will become the Egyptian god of ice and snow.
Felix is channeling Khione from The Heroes of Olympus
- That's why Khione has become so much more powerful and active in the world recently: she now has a mortal avatar binding her to the world.