The long delay was caused by me getting around to reading the English translation of Rewrite. If the story suddenly starts having Key-ish elements in it, that's why.
BGM Set
[X] Fully embrace the dreams.
[X] Deciphering the runes on your books; learning to read.
[X] Create more complex wire patterns.
The dreams move on from the wintry castle into a new setting. You and Kiritsugu have spent many years preparing for this event; a war that takes place in the shadows. You will support him to the best of your ability until it comes time for you to fulfill the role you were created for.
In the meantime, you fully enjoy walking down the street like any normal pedestrian with the golden-haired servant called upon to aid your husband. There is nothing like your approaching demise to make you fully appreciate all of life's small wonders.
When battle comes, you are mostly a passive observer. You were not designed for combat, so you do little in the conflicts yourself. Saber is everything you and Kiritsugu could've hoped for. It makes you sad that she and Kiritsugu seem destined not to get along, and there isn't anything you can do about it.
Your husband's ruthless side is on full display in this shadow war. You wish for nothing more than for Kiritsugu to reach his ideal, so that he never has to stain his hands with blood again. His tactics prove effective, however, and eventually there is only one final opponent left. Before you succumb to the wellspring of energy flowing into you, you have a final conversation with him. He was searching for something in your husband, and clearly did not find it. You have faith to the very end that he will defeat the empty man in front of you. He knocks you unconscious before leaving for the final confrontation.
In an odd omnipresent state, you see your daughter held lovingly in your arms. From the core of your being, you wish for her safety- hoping beyond hope that your wish will carry onto whatever you become next. You pass on peacefully with that gentle image emblazoned into your mind.
Something clicks into place after the dream finishes. You settle more firmly into a certain pattern of thinking, and instinctive knowledge and experience flow into your subconscious mind. You don't think you'll have any more dreams of Irisviel.
Trait lost: Emotionless
Trait increased: Curious E
Trait gained: Playful F-
Trait gained: Innocence (False) D
When you wake, you throw yourself into crafting in a trance, remembered motions and exercises flowing naturally. Material is created in your cupped hands as you weave strands of energy from an imagined core of power. A wire outline of a tiny four-legged creature looks up at you, its head tilted sideways inquisitively. You stare back at it, still half-asleep. It dissolves into the air, and you blink sleepily.
"Hwah-?"
Skill improved: Creation and Forging F
Skill improved: Creation and Forging F+
The mysterious glyphs engraved on the books your mother reads to you capture your imagination. Your determination to learn to read like your mother shows itself in the way you spend long hours in the library with and without your tutors. Any time you are discouraged with your rate of progress, you need only look at the rows of bookcases containing information you can't yet access to rekindle your fighting spirit. It could be considered unnatural the way you dive into reading, but without any children your own age around, this is the only thing you can do for fun.
Your intense concentration in your reading is broken when your mother comes to you with grave news. Her face is ashen, and her eyes are red from crying. She hugs you forcefully as further tears streak down her face. You can only return the hug, getting caught up in the mood as you also begin to cry. "M-mommy..?"
"Your father.. h-he's.." She struggles to get the words out. "..not coming home anymore.."
An icy hand seems to grip your heart as you listen. Even though you can feel the weight behind her words, they don't seem to properly process in your conscious mind.
"But.. he'll be back someday, right..?"
Your mother weeps harder, hugging you even more tightly to her breast.
"No.. he won't."
The rest of the day is a blur. You want to latch on to your mother, but she has to spend a lot of time planning the funeral, so you spend most of your time quietly reflecting. A somber air has descended on the castle, and it doesn't look like it'll leave any time soon.
Your father is gone. How do you mourn?
[ ] You feel depressed. He's gone.. and he's never coming back.
[ ] You feel angry. Why did this happen? What kind of world allows this?
[ ] You feel confused. Why won't da come home? You don't understand.
[ ] You feel shocked. This isn't real, is it?
What do you do in your free time?
[ ] Spend time with your mother in the castle.
[ ] Bug your mother about seeing new places, and meeting more people.
[ ] Spend time with the castle residents.
[ ] Work on your 'special talents.'
(GMNote: I apologize for killing off your dad, but I couldn't really see any way for you to affect that outcome. I can assure you you'll definitely have a say in the 'insanity potion' event. It could turn out better or worse.)