Disclaimer: I do not own anything from Harry Potter or His Dark Materials.
Chapter 5: Severus
Severus always had a hard time making friends, but it wasn't his fault that most children his age couldn't appreciate his maturity and intellect. He would just do as he pleased, when he pleased. As long as he had Ciardha, he didn't need anyone else. That was, until he met Lily. Severus was amazed that she talked to him, and no matter how grumpy and unapproachable he seemed she continued to be his friend. He hadn't realized how much she and Azriel had chipped into his and Cia's heart until his fifth year. He hadn't meant to call her that, it just came out. And when he tried to explain to her, she just brushed him off with Azriel trotting behind her. That was what hurt the most. He and Lily, they told each other everything. Now that he had screwed everything up, she hadn't even told him that Azriel had settled into a Sand Cat.
For his remaining years at Hogwarts Severus allowed himself to be drawn into a group of blood purists that persuaded him into joining an uprising wizard that had power even beyond that of Dumbledore's. Severus just couldn't stand to be on the losing side. The day he took his mark Ciardha changed. No longer did she take her normal forms of wolves, foxes, and ravens. That day she shifted and Severus felt his stomach droop in anticipation. His soul was that of a bat. So be it.
Author's Note:
I just wanted to explain the reasoning behind Severus's form. I know that on Fanfic especially, he is referred to as a "dungeon bat" but that is not why I chose it. I actually wanted to go with something like a Raven, or a black fox, but I felt that the bat actually fit his character better.
The specific bat I chose is the Comoro Black Flying Fox: a person with a bat daemon is known to be difficult to understand, somewhat aggressive, visually intimidating, specialized in a certain social niche, not extremely sensitive or empathetic, and tends to do whatever they want regardless of others.
Although a lot of people idolize Severus for his sacrifices in the book, I decided to make his choice to becoming a death eater his defining moment. Ciardha shows that by representing his true character at that moment.