Material Days (Also being posted in the AnimeSuki Forum's Nanoha FanFiction Discussion and here, though you will need to dig) is a Lyrical Nanoha fanfic by Nanya and Epsilon Zeta (aka Yasanagi on AnimeSuki).Taking place six months prior to Magical Record Lyrical Nanoha Force, when an excavation team uncovers lost scriptures from the Book of the Silver Cross, Yuuno gets called away from his civilian life to lend his expertise to the case, but things get really weird really fast when he finds the excavation site blown to smithereens and the Huckebein fighting... the Materials? Yeah baby, it's everyone's favorite Evil Twins from The Battle Of Aces, and things are about to get very very interesting for our dear Ferret Boy...
This fanfic contains examples of the following tropes:
The casual wear for Material-S is based off Ranpha's cheongsam from Galaxy Angel while Material-D's casual wear is copied from the first appearance of Aizawa Sakuya in Hayate the Combat Butler. The latter is a bit of an interesting case since Sakuya's overall character appearance is very similar to Yami's with the hair and eye colours and the hairstyle.
Awesomeness by Analysis: Material-D has shades of this. By modifying one of her spells and observing the effect when it hit Arnage, she was able to reasonably estimate her enemy's rate of Regeneration and Magic Neutralization. Of course this goes out the window when Arnage Reacts.
Berserk Button: Any mention of the Materials' original counterparts would trigger this to them.
Brick Joke: Rai asks Garyuu to "show me your moves". Later, when Garyuu is about to attack Seikou, she interrupts and tells him that he was supposed to show HER his moves, not Seikou/Material-S
Call Back: In Dieci's words: '"Nanoha-san blew me up when I was a bad guy. Now I'm not a bad guy and evil Nanoha-san is going to blow me up." Tears started to flow down her face. "I don't wanna explode in pink again!"'
Deadpan Snarker: Anyone who hangs out with Material-L long enough is guaranteed to have this role thrust upon them at some point. Vulnificus and Yuuno have had their moments. And now it's Sette's turn.
Ready for Lovemaking: While not in the pose, Seikou tells Yuuno that if he wants to do that with her, he should see her later.
Self-Fulfilling Prophecy: Under Yuuno's influence, the Materials were starting to reform, but the TSAB's insistence on seeing and treating them as the enemy is creating the very opponent it is afraid of.
Senseless Sacrifice: Reinforce Eins's, since the Materials were made from remnants of the corrupted Defence Programme that got away.
Tempting Fate: Chrono's 'At least there isn't someone who looks and sounds like Nanoha with them'. Some time later, Material-S shows up.
One engineer states that "a private call to the Admiral could end up getting transferred to the bridge. Worst case scenario, some media station on Mid-Childa or a public domain television like in a mall". Guess what.