Severus Snape was finishing the last sweep of his patrol as he made his way to the Headmistresses office. She had sent him a note nearly an hour ago requesting he presence as soon as he was able. He scoffed at the notion that she had written it in such nice manner, clearly trying to hide the fact that it was not an optional request.
Severus hoped it had something to do with Miss Granger's punishment, and steeled himself for a battle of the tongues. He was sure that Minerva would have gone too easy on the Gryffindor princess and was now waiting to beg him to take her back into his class.
He knew he would eventually agree, as apart from the fact she was one of only several nearly competent students, he also wanted to find out what had caused her performance in class. He would use his Slytherin cunning to ensure that he garnered the information he wanted in return for her chance at a potions NEWT.
He allowed himself a smirk as he reached the entrance to the Headmistress's office. He was just about to enter, when out of the corner of his eye he caught a flash of silver. He turned his head quick enough to establish that it had indeed been a patronus charging across the courtyard, although not quick enough to note more than the fact it had been some sort of large animal.
Shaking his head, he muttered 'bludger' at the gargoyle who quickly sprang to life granting him entrance.