ana-answers:

Sure!

Laura sees the world in stark blacks and whites at the beginning of the series. She sees the Dean as Evil, no matter what. It isn’t until afterwards, when she starts to see the toll that the Dean’s death has had on Carmilla and the power vacuum it created, that she starts to appreciate the gray. 

The Dean died in a very abstract sort of way. She fell into a pit with the fish. It’s easy to just brush it off as a tragic accident and to not really assign a lot of self-blame to what happened. 

With Vordenberg, Laura does not have that ability to shuffle blame onto happenstance and compartmentalize away the death as not really her fault. She has to make the choice to take his life to save Carmilla knowing that the only way to do that is to effectively end Vordenberg’s life. Sure, he might have been making a play at a small dictatorship, but that does not mean he deserved to die. Laura knows this. She knows this and she’s seen it in action (with Danny and with Mattie) and she does it anyway.

Laura falls apart in the finale because of this. because she knows that she made a choice to save Carmilla over her own moral innocence. She’s putting on a brave face now, because let’s be real, the girl has always been really good at compartmentalizing and putting on a brave face. Still, it’s obviously on her mind.