Magnus was startled when Alec just slumped into him, tall body folding in. They hadn't known one another long, but Magnus knew Alexander well enough to know that he didn't like to be seen as weak. Magnus would never have found him weak for this, anyway, but Alec was young and still full of pride, and he just ... wouldn't have expected the movement, at least not this soon.
But he wrapped an arm around Alec, pulling him in close and bracing to hold them both up. "I know you Shadowhunters believe you have to stand tall in the face of everything. But you're still mostly human, Alexander. You didn't ... let it happen, if it did. It just happened. There are creatures in the world that exist only to take things away. They're not careful who they hurt, or who they use. What happens is their doing, not the people who are run over on the way." He tipped Alec's face up to look at him. "And Clarissa has ... a very big heart. More heart than sense, I would say. It may not be easy for either of you, but she'll forgive you. Because she knows the same thing I do. You, Alexander Lightwood, wouldn't have killed her mother. People keep saying it because it's true, irritating as that probably can be."