"..." Sirius was silent, but he was silent in a very loud way, sighing and shuffling and clearly wanting the attention. But, as he wasn't getting it, he finally just grabbed the book, got up and looked at Remus. "I'll help you study. But outside."

It was a sunny day, they hadn't had that in a while. They were in Scotland, every ray of sunshine had to be valued. "I don't want to stress you out by giving you a choice," he told his friend, considerate as he was.

Then he ran off, of course only after having made sure that the book he was nicking wasn't one of the ones that would hex him if he removed them from the library. Should be fine, as long as he stayed on school property.

Sirius kept running, but he didn't run that fast. He didn't have to, he knew Remus was slow unless he turned furry.