Aries had found the textbook earlier in the day and taken it back to his room to have a good read. It hadn't even occurred to him that he might need to ask Scorpius for the book. After all... was it Scorpius who had paid for it?
Not to Aries' knowledge. He imagined their father had bought it. And if their father had bought it, then Aries had just as much right to it, yes?
That was his way of thinking on it, anyway.
Just in case Scorpius didn't see it this way, he had drawn the curtains around his bed while he read to keep Scorpius from accidentally spotting him with it.