<p>In the Heaven's Feel route, yes, as she says she is in the True End:</p>

<blockquote class="spoiler">
  <p> After Shirou kills Kotomine and is about to sacrifice himself to stop the Greater Grail, Ilya appears wearing the Dress of Heaven planning to shut it down herself. Here she tells Shirou that it's her duty as his older sister to protect him.</p>
</blockquote>

<p>In the Unlimited Blade Works route, however, she doesn't</p>

<blockquote class="spoiler">
  <p> as when Shirou and Rin go to recruit her to help fight Caster, Gilgamesh has already arrived before them, defeated Berserker, and ripped out Ilya's heart, killing her.</p>
</blockquote>

<p>I am unsure about the Fate Route; to my recollection, Shirou doesn't find out (am currently replaying) and I have yet to play Fate/Hollow Ataraxia. However, because it also has hints of all the Fate/Stay Night routes in it, I would assume the knowledge of Ilya and Shirou being adopted siblings is assumed.</p>

<blockquote class="spoiler">
  <p> Of course, Ilya won't admit this to Shirou anyway in Fate/Hollow Ataraxia as the Shirou in it is not actually Shirou but Avenger assuming Shirou's form and Ilya seems to be aware of the False Grail War.</p>
</blockquote>

CC BY-SA 3.0
2015-01-08T23:46:14.993Z
Isn't Shirou unconscious by that point in the HF ending, though? Illya definitely tells him, but I don't think that Shirou actually hears her.
senshin
CC BY-SA 3.0
2015-01-09T00:22:34.090Z
@senshin i'm quite sure he was conscious because if i remember correctly he is about to project Excalibur but realizes it wont be enough and that's when Ilya turns up
Memor-X
CC BY-SA 3.0
2015-01-09T00:23:03.733Z
Oh. I guess I'm not remembering that part correctly. Cool.
senshin
CC BY-SA 3.0
2015-01-09T10:56:32.140Z
I thought he found out much earlier in HF. That the knowledge helped move him to swear off Kiritsugu's ideal because of what it did to her. Though I have nothing to back this up with, so maybe not.
zibadawa timmy
CC BY-SA 3.0
2015-01-09T11:13:52.490Z
@zibadawatimmy I think the part your thinking of is when Shirou abandons Kiritsugu's ideal because to follow would mean he would have to kill Sakura (kill one to save many). I can't remember when the choice actually appears was but i'm sure it's roughly when Sakura is treated by Kotomine and she then runs away, Shirou find out and gives chase and finds her at the bridge and Shirou promises to protect Sakura and that's when they share their embrace in the rain.
Memor-X
CC BY-SA 3.0
2017-03-07T17:18:49.100Z
im confused, if shes his older sister, then at the begining of unlimited blade works, why does she call him big brother
NOnneeddddd
CC BY-SA 3.0
2017-03-07T21:13:31.223Z
@NOnneeddddd i would assume Ilya used the term *"onii-san/chan"* which in same cases would get translated to be big brother but there are times where it isn't used for an older bother like in *School Days* (see the last spoiler in [this answer](http://anime.stackexchange.com/a/3989/1587))
Memor-X
CC BY-SA 3.0
2015-01-08T21:29:59.837Z
2015-01-08T23:47:43.500Z
2015-01-08T23:47:43.500Z
Memor-X
<p>Does it ever get explored in any of the materials? Does he ever find out?  It seems like she knows about him.  </p>

CC BY-SA 3.0
2015-01-08T20:39:31.343Z
Illya definitely knows that Shirou is Kiritsugu's adopted son. I don't remember off-hand when/where Shirou finds out that Illya is Kiritsugu's daughter, though.
senshin
<fate-stay-night>
Does Shirou ever learn about Illyasviel being Kiritsugu's daughter?
# Does Shirou ever learn about Illyasviel being Kiritsugu's daughter?
Posted by: username_0 on 2015-01-08
Does it ever get explored in any of the materials? Does he ever find out? It seems like she knows about him.
**Tags:** fate-stay-night
> **Comments:**
> **username_1**: Illya definitely knows that Shirou is Kiritsugu's adopted son. I don't remember off-hand when/where Shirou finds out that Illya is Kiritsugu's daughter, though.  
---
## 1 answers
### Answer by username_2 on 2015-01-08. Score: 2
In the Heaven's Feel route, yes, as she says she is in the True End:

> After Shirou kills Kotomine and is about to sacrifice himself to stop the Greater Grail, Ilya appears wearing the Dress of Heaven planning to shut it down herself. Here she tells Shirou that it's her duty as his older sister to protect him.

In the Unlimited Blade Works route, however, she doesn't

> as when Shirou and Rin go to recruit her to help fight Caster, Gilgamesh has already arrived before them, defeated Berserker, and ripped out Ilya's heart, killing her.

I am unsure about the Fate Route; to my recollection, Shirou doesn't find out (am currently replaying) and I have yet to play Fate/Hollow Ataraxia. However, because it also has hints of all the Fate/Stay Night routes in it, I would assume the knowledge of Ilya and Shirou being adopted siblings is assumed.

> Of course, Ilya won't admit this to Shirou anyway in Fate/Hollow Ataraxia as the Shirou in it is not actually Shirou but Avenger assuming Shirou's form and Ilya seems to be aware of the False Grail War.
> **Comments:**
> **username_1** (2015-01-08): Isn't Shirou unconscious by that point in the HF ending, though? Illya definitely tells him, but I don't think that Shirou actually hears her.  
> **username_2** (2015-01-09): @senshin i'm quite sure he was conscious because if i remember correctly he is about to project Excalibur but realizes it wont be enough and that's when Ilya turns up  
> **username_1** (2015-01-09): Oh. I guess I'm not remembering that part correctly. Cool.  
> **username_3** (2015-01-09): I thought he found out much earlier in HF. That the knowledge helped move him to swear off Kiritsugu's ideal because of what it did to her. Though I have nothing to back this up with, so maybe not.  
> **username_2** (2015-01-09): @zibadawatimmy I think the part your thinking of is when Shirou abandons Kiritsugu's ideal because to follow would mean he would have to kill Sakura (kill one to save many). I can't remember when the choice actually appears was but i'm sure it's roughly when Sakura is treated by Kotomine and she then runs away, Shirou find out and gives chase and finds her at the bridge and Shirou promises to protect Sakura and that's when they share their embrace in the rain.  
> **username_4** (2017-03-07): im confused, if shes his older sister, then at the begining of unlimited blade works, why does she call him big brother  
> **username_2** (2017-03-07): @NOnneeddddd i would assume Ilya used the term *"onii-san/chan"* which in same cases would get translated to be big brother but there are times where it isn't used for an older bother like in *School Days* (see the last spoiler in [this answer](http://anime.stackexchange.com/a/3989/1587))  
---
