"Someone's coming down for you," said Tonks. "Look."
A lantern was bobbing at the distant foot of the castle. Harry was so pleased to see it he felt he could even endure Filch's wheezy criticisms of tardiness and rants about how his timekeeping would improve with the regular application of thumbscrews. It was not until the glowing yellow light was ten feet away from them, and Harry had pulled off his Invisibility Cloak so that he could be seen, that he recognized, with a rush of pure loathing, the uplit hooked nose and long, black, greasy hair of Severus Snape.
"Well, well, well," sneered Snape, taking out his wand and tapping the padlock once, so that the chains snaked backward and the gates creaked open. "Nice of you to turn up, Potter, although you have evidently decided that the wearing of school robes would detract from your appearance."
"I couldn't change, I didn't have my--" Harry began, but Snape cut across him.
"There is no need to wait, Nymphadora, Potter is quite--ah--safe in my hands."
"I meant Hagrid to get the message," said Tonks, frowning.
"Hagrid was late for the start-of-term feast, just like Potter here, so I took it instead. And incidentally," said Snape, standing back to allow Harry to pass him, "I was interested to see your new Patronus."
He shut the gates in her face with a loud clang and tapped the chains with his wand again, so that they slithered, clinking, back into place.
"I think you were better off with the old one," said Snape, the malice in his voice unmistakable. "The new one looks weak."
As Snape swung the lantern about, Harry saw, fleetingly, a look of shock and anger on Tonks's face. Then she was covered in darkness once more.
~Half-Blood Prince, Ch. 8, "Snape Victorious"
I think I'm going to have to take this quote bit-by-bit. First off, I love the name of this chapter. Any chapter with 'Snape' in the name is obviously going to be good.
And it's pretty ironic how, while Harry feels a rush of loathing when Snape enters the scene, we all feel very excited and our blood pressure rises. Also, at 'uplit hooked nose,' I had a crazy thought about Snape trying to be like Narcissa, who has a very upturned nose... If Snape was to turn his nose up at something, his head would have to be tilted back at a ninety degree angle with his neck.
Then, of course, I love how Snape calls nearly everyone by their last name, but he calls Tonks by her first name just because he knows it makes her angry. It would be hilarious if he called her 'Tonkadora.' XD
And we all know Harry's safe in his hands... God, I want to be in his hands. *jealous*
Oh--and as for the Patronus thing, I suppose Snape must have known about Tonks and Lupin. And he clearly does not ship them.
Overall, this is just a really nice quote, because it shows how sometimes Snape is just cruel for fun, and how it's so sexy to us. ^_^