Remus didn't have to look up to know who entered the room. Somehow, he always just knew when Sirius was around. It was as though his senses were more finely tuned to this mate of his. That and also because Sirius Black was just someone who automatically commanded attention.
But just to tease his friend, Remus pretended to still be very much absorbed in his book. Sirius didn't need to know that he always had Remus' attention. All of his attention. Remus couldn't bear to think of how much Sirius' ego would inflate if he knew. "Yes, Padfoot?" Remus asked, not looking up from his book.