Why did you?” Clary asked.
“Why did I what?”
“Help me back there.”
“You’re my sister.”
She swallowed. In the morning light, Sebastian’s face had some color in it. There were faint burns along his neck where demon ichor had splashed him.
“You never cared that I was your sister before.”
“Didn’t I?” His black eyes flicked up and down her. “Our father’s dead,” he said. “There are no other relatives. You and I, we are the last. The last of the Morgensterns. You are the only one left whose blood runs in my veins, too. You are my last chance.

Cassandra Clare