Irisviel von Einzbern (アイリスフィール・フォン・アインツベルン, Airisufīru fon Aintsuberun?) is a homunculus. She is the wife of Kiritsugu Emiya and the mother of Illyasviel von Einzbern.

Irisviel claims that seeing him introverted makes her very sad, and after using his True Name, EMIYA immediately tells her never to do so again and thus, Irisviel runs away in tears. She says that no matter what world he is from, she will still love him and refers to herself as his wife.

When Kiritsugu shoots the hallucination of Illya between the eyes and she falls over "dead," the Avenger-possessed Irisviel lets out a gut-wrenching, heart-breaking shriek of abject horror and sadness that just tears at you when you hear it.

I know the show mentions she’s a homunculus, but what is her purpose exactly? And again where is this mentioned in the show? I’m just confused as to the ending of fate zero; does kiritsugu actually kill irisviel or does he kill an illusion of the holy grail?

Irisviel had a look of kicked puppy on her face and looked as if she was about to cry. The red-clad Servant justsighed a little. "Truly, Master, do you think a few crocodile tears will get me to wear that?"