A Case when Rin Tohsaka goes to the Promise Land
Rin Wins the Holy Grail War alongside Archer, but when her wish to reach Akasha is granted she is sent to Gaia. Appearing in MT Nibel where she meets stubborn Blond kid with impossible hairstyle who is asking her to teach him how to use magic.
Rin Tohsaka + in a world filled with Materia crystalized Lifestream + Nasuverse Mechanics= Interesting.
The Mechanics would not be so different from Nasuverse its safe to presume that Alaya and Gaia are the same entity since the world named Gaia is Akasha to Rin, because the Heroes and Monsters are stored within the Materia which comes from the lifestream which is the lifeblood of the planet which also carries the memories.
It possible to presume that Archer ends up in a summon Materia. It is possible that it can be applied the Class Card system of Fate Kaleid on this case instead of cards is Materia to be more precise Summon Materia.
Given that Akasha is basically the knowledge of all and the lifestream it carries knowledge all.
Rin is a magus who specializes in jewel thaumaturgy which practiced her entire life. Now putting her in world which produces absurd amounts of jewels (Rin pov) with mana stored within them for many hundreds or thousands of years, it will be mind-blowing for her. And superhuman who can store more of that mana within them would make her want abduct one.
When she picks a student which want to be turned into one of those superhuman, she will make everything in her power for him to succeed.
Cloud Strife: Being a child he meets a strange woman who saves Tifa and his lives, and later see said woman moving into the old Mansion in Nibelheim.
Number of Circuits:
Rin Tohsaka: A mysterious woman which moved to the Shinra mansion.
Butterfly Effect by Kiraya: A story with a development which ending traumatized, still quite good with world development and Shinra Bureaucracy mechanic.
Valentine's Day by Umei no Mai: An awesome story which starts with an impossible event Vincent being born a girl, not a lot of world development as Butterfly Effect but is quite good material. With financial coups.
The Turks' Way by LunaStorm: This one though short and funny show the creation of an Information network.
Harry Potter and the Methods of Rationality by Less Wrong: Harry trying to discover how the magical world works through science.
Terrorism & Anarchy by VarianN:
Border of Taboo by xLilly White: How the Business of Brothels works in Midgard.
Ripples in Time by Shivavixen: Politics.
Professor Strife by Basilton: Is the title and the first chapter. If it leaved untouched the theme of time travel and used the theme divergence it would have been an awesome development.
By a Fraction Degree by findthetiger: A divergence with its own world development plus economy.
Cissnei's Path by CRed1988: A divergence with world development, organized team work.
The Fifth Act by Sinnatious:
The Hill of Sword by Gabriel Blessing:
Fate: Shattered Moon by Trick N. Zwei: Jewels Magecraft being compared with Dust. Replace the dust with Materia and we have Materia Magecraft.
Another Idea it would be interesting to see it being made anyone interested in adopting it, feel free to adopt it.