When Rin stopped coughing I kneeled by her side.
-"Sho shandn't 'ave cashted ith iff tong."

-"Whet? I cansh unyershtan shou."

I took out my torch and started to write again.
You shouldn't have casted Gandr with a stiff tongue.
Any magus knows how sensitive is each incantation.

She tore the notebook from my hands and started to write furiously. Her calligraphy was impeccable, speaking volumes of her dedication to excellence in any endeavour she attempted.
I have mastered the Gandr by the age of eleven, thank you very much!
She stopped writing and eyed me, her twin aqua orbs shining in the dim light.
For someone incapable of casting anything, you are well learned enough.
Now, aren't you going to finish me off?

At this, she pointed to my sheathed knife.

I extended my hand towards the abused notebook and she shoved it into my hands.
It never crossed my mind to harm you, Rin.

She gave me an eye roll.
You certainly scared me to an inch of my life.
Are you a natural moron or they dropped you as a child?

No need to get petty.
I stopped writing and eyed her.
Taking my knife in my hand, which caused Rin to stiffen, I pierced my skin and then applied the coated blade to the parchment.
A ritual old as time itself, even I was able to use this simple magick.
I, Shiriou from the clan Emiya, on the Root and by magic vow, that I care for your wellbeing.
The text came alight with mana, casting arcane light into the cave walls.

Rin declined to touch my knife, but instead bit her own pinky.
I, Rin of the clan Tohsaka, eldest child and heir, won't threaten you again to disclose your status as Incarnation, on the condition that you tell me your affinity.

No words were needed, for they were integral to my being. I couldn't use any other magic, so I focused on my own skill to a degree that even dad considered unhealthy.
When I wanted to use a tool, when I wanted to cast something to remind myself that I am a real mage, when I was bored, and when I needed a weapon.
I would use Gradation Air. Again and again, until I started to tweak it. This is how I cast it.

Judging the concept of creation.
Hypothesizing the basic structure.
Duplicating the composition material.
Imitating the skill of its making.
Sympathizing with the experience of its growth.
Reproducing the accumulated years.
Excelling every manufacturing process.

And I did not need to speak the words that unleashed that trigger.
For they were part of my very soul.
Trace
ON!