Sirius was in a rather broody mood, and had stormed the entire way to the library, where he knew Moony would be.
He hoped his friend was ready to die. Because Sirius was feeling murderous. He wondered briefly what Madam Pince would do if he got blood on her books, and decided that he would be better off doing it in a less messy manner.
He reached Remus and Mary's study spot just in time to hear Remus's declaration, and glared.
"Keep your lips off my girlfriend, you wanker," he ordered, pointing an accusing finger at his so-called best friend.