As she looked, the smoke puffing out of the chimney stopped curling upward and began to take on the shape of a wavering black question mark.
Sebastian laughed. "I think that means, Who's there?"
Clary pulled her coat closer around her. "It looks like something out of a fairy tale."
"Are you cold?" Sebastian put his arm around her. Immediately the smoke curling from the chimney stopped forming itself into question marks and began puffing out in the shape of lopsided hearts.

Autore: Cassandra Clare