this is touching, Severus,” said Dumbledore seriously. “Have you
grown to care for the boy, after all?”
“For him?” shouted Snape.
From the tip of his wand burst
the silver doe: She landed on the office floor, bounded once across
the office, and soared out of the window.
This exchange appears in Chapter Thirty-Three,
though it takes place before the events of this novel. This is one
of Snape’s memories that Harry views through the Pensieve after
Snape’s death. In it, Dumbledore has just revealed that he has known
for a long time that Harry will have to die before Voldemort can
be killed. Snape accuses Dumbledore of lying to Snape and using
him, because Dumbledore had told him years before that he could
protect Lily Potter’s son (Harry), which is the sole reason Snape
has devoted himself to this dangerous project. In these lines, Snape
makes it clear that his love for Lily Potter has always been his
motivation, demonstrating this fact in the dramatic visual image
of his own Patronus, which takes the same form that Lily’s did—that
of a doe.
Dumbledore’s words are wonderfully ambiguous. When Harry sees
this conversation, he is learning for the first time that he has
to die, and that Dumbledore knew this and deliberately kept it from him.
Dumbledore’s words may or may not be sarcastic, may or may not suggest
that Dumbledore does not care for Harry, may or may not imply that
Dumbledore has been using Harry.