The first thing Irisviel remembered was a flame.
She could not tell you when exactly this was. It was in the "before"—the time when nothing mattered but the certainty that eventually she would fulfill the purpose of the Holy Grail War. The time before she had a purpose of her own instead. The time before Kiritsugu's weary smile and Ilyasviel's soft body in her arms.
The first thing she could remember was sitting up straight in a cold room of the Einzbern castle, staring at a candle resting in a sconce on the wall opposite her. She sat there and she watched the flame dance, and she noted that it was beautiful, and she would not be able to see without it. After a while, she noted another thing: the candle was disappearing. The beautiful flame ate away at the wick and the wax even as it used them to cast light.
She must have still been very young then, because she recalled that she wondered if the flame sorrowed in its existence. She did not know then that flame has no consciousness, no awareness at all. It made sense to her that it would, because she was an object, and she had a consciousness.
She learned otherwise later. But at the time, Irisviel wondered about the flame, and it might have kindled something in the layer of artifice that was her heart.
The first thing Irisviel remembered about Kiritsugu Emiya was watching from a window as he stood outside and lit a cigarette as he examined the Einzbern castle.
She could not tell you exactly what he was doing. She did not classify him as important enough to remember such minutiae then. She remembered watching the flame of his lighter dance around his fingertips, though. She remembered thinking that breathing in smoke and ash was a terrible habit to have, and that it was strange that this man's face did not change in the slightest as he drew upon the cigarette.
But even then, she knew that there was something like the flame in his eyes. There was something pure and self-destructive in the light inside those shadowed eyes.
It was not until Irisviel saw Kiritsugu weep that she understood something vital about him.
He had her in his arms at the time—later, she would learn that he had pulled her battered body out from the winter forest where Jubstacheit had thrown her to prove the resilience of her body. At that time it would strike Irisviel as really strange that Kiritsugu had rescued her, since he was the one who had demanded she be tested. But for now, dazed from exposure and shock, all she knew was that there was pain and anger on his face, and tears were falling to strike her face as well.
They were hot, like they'd been warmed by a flame.
Irisviel understood then: there was fire in his tender heart, eating him up as it burned.
There was a night when Irisviel woke up from troubled dreams to find Kiritsugu weeping into her hair.
Still half-asleep, she wondered if she was burning. The wet, sticky heat should have been the opposite of the dry heat of a flame, but to her it felt the same. So she reached up to hold him close and whispered, "You're burning up, my love. You're burning up." She was not awake enough to make more sense than that.
"Let me burn," he said.
"I refuse," she said. "I'll give you a heart that can withstand the flames, my love. I have no greater purpose."
How could he keep burning so brightly without suffering so greatly? That was her only answer.
For years Irisviel thought that Kiritsugu Emiya was the only one who could burn so brightly with such a gentle face, but there came a time when she realized she was wrong.
In the shadow of the Holy Grail War, Saber took Irisviel's hand in hers, and Irisviel was astonished to feel how warm it was. But that was strange. Why should she be so surprised? Saber might have been a glorious hero, but she possessed a human body like anyone else. Of course her hand was warm.
But Irisviel had been foolish. She'd expected someone so pure and bright to be cold, even though she should have known better. She knew that people could be like flames, because she loved Kiritsugu. Why should she be so surprised to find another like him?
She held Saber's hand as they walked through the town, and she wondered how many people there were like that in the world, people whose hearts were on fire within a cold exterior. She did not know, but she knew one thing: she was blessed to have met two of them.
Perhaps she was foolish again, but she was certain that no others could shine as brightly as these two. There were none whose hearts burned like her love or her knight.
When the light of Excalibur rose from the water, Irisviel was not looking at what everyone else was looking at.
They saw the brilliant light of the sword, and that was beautiful enough, but Irisviel saw the figure of the woman beneath it. How could such a small body ever contain such perfect light?
Standing there on the banks of the river, Irisviel smiled. She clasped her hands over her heart.
"I'm so glad," she whispered. "I'm so glad I could burn for them as they burned for the world."