<p>Actually this is not the case and is a common example of where the plot falls apart between cannon and filler. </p>

<p>This is a long answer and took a lot of editing, but try to stay with me and feel free to comment if anything doesn't make sense. First, I will explain why your question doesn't have an answer, then I will explain why.</p>

<p><strong>First off,</strong> </p>

<blockquote>
  <p>The reason why the queen killed Ciel's parents</p>
</blockquote>

<p>This is unknown because it is never <em>truly</em> revealed in the anime. In the battle it is alluded to that the queen perceived Phantomhive household as a threat to the throne and had them exterminated. As to why they became such a threat is left unclear.</p>

<p><strong>Secondly,</strong></p>

<blockquote>
  <p>Why is this unanswerable?</p>
</blockquote>

<p>The contract that Ciel has with Sebastian pertains specifically until Ciel satisfies his revenge. So once that enemy is listed and the conflict is resolved, the plot would end <em>theoretically</em>. As you probably already know, the manga for this series is still being written by <code>Yana Toboso</code> so naturally the <strong><em>main</em></strong> villain has yet to be revealed and we are still learning the history of Vincent's past bit by bit as Ciel goes through his adventures in service to the crown.</p>

<p>The concept of the queen being the killer of Ciel's parents was only explored in the anime and IMHO was a fantastic plot twist to keep the anime below 25 episodes and very enjoyable, but...</p>

<p><strong>The black butler anime is only partially canon.</strong> </p>

<p>The deaths of Ciel's parents have yet to even be explored in the manga. For this reason (among several other inconsistencies with the manga), the anime has several plot holes. If you watch the first season to completion and then watch Book of Circus or Book of Murder (both of which are canon), then the plot clearly falls apart.</p>

<p>Black Butler II and everything that happened in the latter half of the anime is <strong>not canon</strong>.</p>

<p>Black Butler contains the following arcs, more details can be read about them <a href="http://kuroshitsuji.wikia.com/wiki/Timeline" rel="nofollow noreferrer">here</a>: </p>

<ul>
<li>Kidnapping</li>
<li>Jack the Ripper (also called the Madame Red arc)</li>
<li>Houndsworth (anime only, non-canon)</li>
<li>Shard of Hope (anime only)</li>
<li>Curry Contest</li>
<li>Noah's Ark Circus (manga only, adopted later in the Book of Circus OVA)</li>
<li>Haunted Castle (anime only)</li>
<li>Book of Doomsday (anime only)</li>
<li>Conspiracy and Revenge (anime only, death of the queen and end of the anime)</li>
<li>Phantomhive Manor Murderds (manga only, later adopted in Book Of Murder OVA)</li>
<li>Luxury Liner (manga only)</li>
<li>Public School (manga only)</li>
<li>Emerald Witch (manga only)</li>
<li>Blue Cult (manga only, and current arc at chapter 117 released June 2016)</li>
<li>Black Butler II doesn't have a place in the storyline as of yet, but will be added at the end here because it does exist.</li>
</ul>

<p>So a prime example of this is that if the queen was killed in <code>Conspiracy and Revenge</code>, why is Ciel still taking a mission from her in <code>Public School</code> which clearly occurred after?</p>

<p>So to sum all of this up, the manga does <strong>not</strong> support the fact that the queen killed the parents of Ciel. So if the anime did not fully flesh out why that happened then there is no answer. </p>

<p><strong>PS: I can list the more major plot differences anime-wise and manga-wise, but it will take me time to look up arc names and whatnot so this answer will be getting edited.</strong></p>

<p><strong>PPS:</strong> Finally finished all my <em>major</em> edits. Anything else beyond this will be for style and added clarity.</p>

CC BY-SA 3.0
2016-06-28T13:01:16.823Z
Is it impossible to explain it using the anime only as the base?
絢瀬絵里
CC BY-SA 3.0
2016-06-28T13:04:55.090Z
Well if we go exclusively on the anime , no. Vincent Phantomhive was a powerful man. So the queen could have had any number of reasons to question his loyalty to the crown. And as you can tell from the anime. Once your marked for death by the queen your time is up. And only the queen would know why.
Callat
CC BY-SA 3.0
2016-06-28T11:53:51.860Z
2017-01-13T12:40:28.943Z
2017-01-13T12:40:28.943Z
Callat
<p>In the anime, <em>Black Butler</em>, while sitting inside the Eiffel Tower, the Queen finally admits to Ciel that she was the one responsible for the death of </p>

<blockquote class="spoiler">
  <p> his parents.</p>
</blockquote>

<p>Why did she kill them, exactly?</p>

<p>We find out later that</p>

<blockquote class="spoiler">
  <p> his parents even knew the Queen may be coming for them,</p>
</blockquote>

<p>but why? </p>

CC BY-SA 3.0
2016-06-28T13:05:34.300Z
There is a proverb (I forget how it exactly goes but the point is the same), a sharp sword is a good sword, a too sharp sword is a dangerous sword (thus needs to be disposed off). The Phantomhive might have grown too powerful that the Queen feel threatened.
絢瀬絵里
<black-butler>
Why did the Queen kill Ciel's relatives?
# Why did the Queen kill Ciel's relatives?
Posted by: username_0 on 2016-06-27
In the anime, *Black Butler*, while sitting inside the Eiffel Tower, the Queen finally admits to Ciel that she was the one responsible for the death of

> his parents.

Why did she kill them, exactly?

We find out later that

> his parents even knew the Queen may be coming for them,

but why?
**Tags:** black-butler
> **Comments:**
> **username_1**: There is a proverb (I forget how it exactly goes but the point is the same), a sharp sword is a good sword, a too sharp sword is a dangerous sword (thus needs to be disposed off). The Phantomhive might have grown too powerful that the Queen feel threatened.  
---
## 1 answers
### Answer by username_2 on 2016-06-28. Score: 5 | Accepted answer
Actually this is not the case and is a common example of where the plot falls apart between cannon and filler.

This is a long answer and took a lot of editing, but try to stay with me and feel free to comment if anything doesn't make sense. First, I will explain why your question doesn't have an answer, then I will explain why.

**First off,**

> The reason why the queen killed Ciel's parents

This is unknown because it is never *truly* revealed in the anime. In the battle it is alluded to that the queen perceived Phantomhive household as a threat to the throne and had them exterminated. As to why they became such a threat is left unclear.

**Secondly,**

> Why is this unanswerable?

The contract that Ciel has with Sebastian pertains specifically until Ciel satisfies his revenge. So once that enemy is listed and the conflict is resolved, the plot would end *theoretically*. As you probably already know, the manga for this series is still being written by `Yana Toboso` so naturally the ***main*** villain has yet to be revealed and we are still learning the history of Vincent's past bit by bit as Ciel goes through his adventures in service to the crown.

The concept of the queen being the killer of Ciel's parents was only explored in the anime and IMHO was a fantastic plot twist to keep the anime below 25 episodes and very enjoyable, but...

**The black butler anime is only partially canon.**

The deaths of Ciel's parents have yet to even be explored in the manga. For this reason (among several other inconsistencies with the manga), the anime has several plot holes. If you watch the first season to completion and then watch Book of Circus or Book of Murder (both of which are canon), then the plot clearly falls apart.

Black Butler II and everything that happened in the latter half of the anime is **not canon**.

Black Butler contains the following arcs, more details can be read about them [here](http://kuroshitsuji.wikia.com/wiki/Timeline):

* Kidnapping
* Jack the Ripper (also called the Madame Red arc)
* Houndsworth (anime only, non-canon)
* Shard of Hope (anime only)
* Curry Contest
* Noah's Ark Circus (manga only, adopted later in the Book of Circus OVA)
* Haunted Castle (anime only)
* Book of Doomsday (anime only)
* Conspiracy and Revenge (anime only, death of the queen and end of the anime)
* Phantomhive Manor Murderds (manga only, later adopted in Book Of Murder OVA)
* Luxury Liner (manga only)
* Public School (manga only)
* Emerald Witch (manga only)
* Blue Cult (manga only, and current arc at chapter 117 released June 2016)
* Black Butler II doesn't have a place in the storyline as of yet, but will be added at the end here because it does exist.

So a prime example of this is that if the queen was killed in `Conspiracy and Revenge`, why is Ciel still taking a mission from her in `Public School` which clearly occurred after?

So to sum all of this up, the manga does **not** support the fact that the queen killed the parents of Ciel. So if the anime did not fully flesh out why that happened then there is no answer.

**PS: I can list the more major plot differences anime-wise and manga-wise, but it will take me time to look up arc names and whatnot so this answer will be getting edited.**

**PPS:** Finally finished all my *major* edits. Anything else beyond this will be for style and added clarity.
> **Comments:**
> **username_1** (2016-06-28): Is it impossible to explain it using the anime only as the base?  
> **username_2** (2016-06-28): Well if we go exclusively on the anime , no. Vincent Phantomhive was a powerful man. So the queen could have had any number of reasons to question his loyalty to the crown. And as you can tell from the anime. Once your marked for death by the queen your time is up. And only the queen would know why.  
---
