"Expecto Patronum!"

Nothing. He concentrated, but his Patronus remained elusive.

After several tries, he threw down his wand in frustration as Potter and Black walked by taunting him. He expected that, but then he noticed that even a few fellow Slytherins were sniggering. He swore they'd all be sorry one day.

After a while, a pretty auburn haired girl approached him quietly.

"Don't worry, Severus. The professor said it was a very difficult spell."

He started to say something sarcastic, but forgot what it was as soon as Lily kissed him.

A few minutes later, a large, silver snake appeared.