Why did Rem kill L?


I know that it was Light's plan to make Misa look suspicious again so that Rem
would kill L. But why did she think that Misa was going to be executed?

Was it because her lifespan was shortened again?

I thought that only a Death Note can shorten the lifespan of a person, and
even though she did the Shinigami eye deal again, was her lifespan too
shortened?

Or can your lifespan get shortened by other people, because of their actions?




Basically, **L told her** what would happen, when she would be caught. Light
made it pretty obvious that Misa was the new _Killer_ , letting all evidence
point in her direction. He made her kill people the instant she left the
mansion. Especially since Misa was the original suspect for being the second
_killer_. If it wasn't for the fake rule, Misa would have been arrested or at
least thoroughly investigated and L had doubts about that rule from the
beginning anyway.

> **L:**  
>  If the murderer by notebook is recognized, at the very least, if we cannot
> get the capital punishment, we would have them write their own name in the
> book. That's how it is. **_chapter 57_**

[![enter image description
here](https://i.stack.imgur.com/veP4Xm.png)](https://i.stack.imgur.com/veP4X.png)

Rem, being pretty sharp herself, came to the same conclusion. She knew L would
figure it out, she knew it would mean the end for Misa. Though, she had made a
promise to protect her till the end, so she knew she had to kill L to prevent
Misa from dying early.

> **Rem:**  
>  The one who is killing the convicts right now is Misa. There is no doubt
> about that. Since the notebook has been revealed, no matter what happens
> from this point on, the one who will be caught as Kira will be Misa. That
> wont change...  
>  Yagami Light is confident that I will save Misa's life... The only way to
> save Misa in a situation like that would be for me to write Ryuuzaki's true
> name in the notebook...  
>  And in that situation if I were to kill Ryuuzaki then I would have clearly
> meddled with Misa's lifespan and die. **_chapter 57_**

[![enter image description
here](https://i.stack.imgur.com/mAcJlm.png)](https://i.stack.imgur.com/mAcJl.png)




Basically, **L told her** what would happen, when she would be caught. Light
made it pretty obvious that Misa was the new _Killer_ , letting all evidence
point in her direction. He made her kill people the instant she left the
mansion. Especially since Misa was the original suspect for being the second
_killer_. If it wasn't for the fake rule, Misa would have been arrested or at
least thoroughly investigated and L had doubts about that rule from the
beginning anyway.

> **L:**  
>  If the murderer by notebook is recognized, at the very least, if we cannot
> get the capital punishment, we would have them write their own name in the
> book. That's how it is. **_chapter 57_**

[![enter image description
here](https://i.stack.imgur.com/veP4Xm.png)](https://i.stack.imgur.com/veP4X.png)

Rem, being pretty sharp herself, came to the same conclusion. She knew L would
figure it out, she knew it would mean the end for Misa. Though, she had made a
promise to protect her till the end, so she knew she had to kill L to prevent
Misa from dying early.

> **Rem:**  
>  The one who is killing the convicts right now is Misa. There is no doubt
> about that. Since the notebook has been revealed, no matter what happens
> from this point on, the one who will be caught as Kira will be Misa. That
> wont change...  
>  Yagami Light is confident that I will save Misa's life... The only way to
> save Misa in a situation like that would be for me to write Ryuuzaki's true
> name in the notebook...  
>  And in that situation if I were to kill Ryuuzaki then I would have clearly
> meddled with Misa's lifespan and die. **_chapter 57_**

[![enter image description
here](https://i.stack.imgur.com/mAcJlm.png)](https://i.stack.imgur.com/mAcJl.png)

