I feel like we don't talk enough about how Spike didn't kill Cecily. Think about it. She, very harshly, rejected and insulted him. Then he became a vampire. A vampire so vicious that he became famous. And yet his first move wasn't to murder the woman who dismissed him like his existence was meaningless. It was to go turn his sick mother into a vampire so she could live forever with him. He loved his mother so deeply that it lingered even after he lost his human soul. I believe the same can be said of his feelings for Cecily, despite her rejection. I mean, he wrote poetry for her. That requires some pretty intense emotions. He could've gone and gotten revenge with his hot new girlfriend, who I am certain would have relished watching him violently kill the woman who caused the tears he was shedding when she met him. You could argue that it was because he fell in love with Drusilla and no longer cared about Cecily. And, if that's the case, it means that he loved her so powerfully that it completely erased his emotions about Cecily, even the negative ones. But I don't think that's it. I think the love he had for Cecily was so powerful that, despite her rejection, and like with his mother, it lingered even when he became a vampire.
This is, I believe, another example of Spike's unique ability to love as a soulless vampire. Angelus murdered his entire family, including his entirely innocent little sister whom he loved, because his father had been a dick to him. Hell, he murdered the entire village. Everyone he'd ever met. Absolutely no part of him had any love remaining.
Whereas Spike was capable of loving so deeply that even after Buffy died, he protected her little sister because he'd promised Buffy he'd protect her "til the end of the world". He thought he would never see Buffy again, so it wasn't like he was trying to get her to fall for him. He did it because he knew she would have wanted it. It didn't matter that he would get exactly nothing out of it. Can you imagine any other vampire in the Buffyverse doing that?
So yeah, Spike didn't kill Cecily and we should talk about that more.
