"For him?" shouted Snape. "Expecto Patronum!"
From the top of his wand burst the silver doe: She landed on the
office floor, bounded once across the office, and soared out of the
window. Dumbledore watched her fly awaym and as her silvery glow
faded he turned back to Snape, and his eyes were full of tears.
"After all this time?"
"Always," said Snape.
Harry Potter and the Deathly Hallows - The Prince’s Tale Page 687