I have wanted to write Illya centered story for a while. Originally this was supposed to be only about Illya waiting for Kiritsugu and Iri but couldn't stop writing and here's the final result. The story takes place during Fate/Zero and Fate/Stay Nigh Fate route/TV series.
Simply Human
Illyasviel's birth was different from most of the children for she wasn't a human. But despite that she was a happy child. She had loving parents and happy childhood with them. But good things never last forever and Illya learned that the hard way.
"When will you come back?" she asked her mother curiously.
Irisviel hugged her daughter tightly.
"I'm sorry, Illya, but mommy isn't coming back..." Iri said through tears.
"Why?" Illya asked her mother innocently.
"Because I want to protect you. You won't have to be scared anymore..." Iri said while stroking her child's hair.
"But papa will come back to you. You two will always be happy together..."
Illya nodded happily.
"Mhm! Kiritsugu always comes back, so don't cry, momma," said Illya while wiping away tears from her mother's cheeks.
Several weeks have passed and Kiritsugu still hasn't come back. But Illya was a patient girl. She knew that her father had some kind of serious business to deal with. Like this a month has passed. Then another and another. A little was spending her days alone sitting by the window hoping for a sign that her father is coming back. And yet, all she could see was blizzard raging outside.
Finally, she gathered enough courage and went to Einzbern family head hoping to find answers. Maybe something bad happened to Kiritsugu and that's why he's late. Was that little has been hoping for. But the answer she found was something else entirely.
"He has abandoned you. Emiya Kiritsugu has another child. He has deceived and betrayed us," Jubstacheit von Einzbern, the 8th head of Einzbern family, told Illya. "But surely you won't do the ame, will you, Illyasviel?"
Illya solemnly nodded.
"Good girl. And never forget what Emiya Kiritsugu has done to you and our family."
She never forgot her father's betrayal. He left her all alone to deal with her nightmares herself. He trated his own daughter for some other boy. Ten years later her heart was still aching from the pain she had to endure all these years. She wanted to get revenge at him but more importantly she wanted to ask "why?". But Illya was too late. Emiya Kiritsugu was already gone. She was able to meet the boy who has stolen her family instead.
In the end, despite everything she couldn't bring herself to hate them. It was too late, anyway.
Shirou Emiya hasn't cried in years. He simply had no tears. But this was different. His little sister slowly and painfully succumbed to death. It has been only few months since the Fifth Holy Grail War has ended. Illya was more than happy living with her "onii-chan". But she never was a human. Only a mere tool created to die. Nevertheless, she was able to feel. And that made her human.
Despite slow and painful death, Illya was able to leave with a smile on her face. Because she wasn't scared anymore. She didn't want to leave but at least she finally would be reunited with her parents.
Shirou took one last glance at Illya's grave before leaving her to rest in peace.
The End
Well, Illya lives in Fate route but due to her being vessel for the Holy Grail, I don't think she would be bale to live for a long time. As for her death, think of Iri when her condition started worsening. Well, that's it. Please review. ^^