I loved the dynamic between Tessa, Will, and Jem right from the start. Tessa's whole journey of self-discovery, being this shape-shifting warlock thrown into a world she never knew existed, really anchors the story. Will Herondale is the classic tortured, sarcastic Shadowhunter with a secret heart of gold, while Jem Carstairs is his complete opposite – gentle, kind, and playing the violin. Their trio is the core.
You can't forget Charlotte Branwell, who runs the London Institute, or Henry with his hilarious, often disastrous inventions. Then there's the villain, the Magister, who's this creepy puppet master figure. Jessamine Lovelace provides some great comic relief as the aspiring mundane socialite trapped in a Shadowhunter's life. Nate, Tessa's brother, causes a lot of the initial trouble too.