Remus was startled by the disturbance. He put down his book, only to find Sirius next to him on the bench. His initial annoyance was quickly replaced by surprise. He had not expected to find Sirius here.
"Sirius!" he was unable to hide the surprise evident in his voice. "Why are you here?"
If Remus were to guess, he would have made an educated conjecture about Sirius flirting with some girl or the other. It was one of the things that happened when you were popular like Sirius or James.
Remus made a face when he heard Sirius say that he was being 'typical', studying already.
"I'll have you know that I am not studying. Incidentally, I happen to be doing a bit os extra-curricular reading."
Remus put away his book, half because Sirius was here and his friend was more important. The other half because, well, Sirius would undoubtedly tease him if he saw the title.