You see, cuckoos are parasites. They lay their eggs in other birds' nests. When the egg hatches, the baby cuckoo pushes the other baby birds out of the nest. The poor parent birds work themselves to death trying to find enough food to feed the enormous cuckoo child who has murdered their babies and taken their places."
"Enormous?" said Jace. "Did you just call me fat?"
"It was an analogy."
"I am not fat.

Author: Cassandra Clare