"Yeah!" Sirius was enjoying this for so many reasons. He had a wand, he had made a friend and his mother wasn't here to correct his speech, so he could say 'yeah' instead of 'yes' as much as he wanted to. Life was pretty grand. "I got loads of money, don't worry about it. I can buy us the biggest ice cream you've ever seen in your life."

Sirius tried to show the dimensions with his hands, then stopped when the bookshop owner looked at them. "There you go, young man."

He was smiling at Severus. And then he looked at Sirius, frowning. "Back so soon? I wouldn't think the young Master Black would just get to run around by himself..."

Sirius squirmed, but grinned, half-hiding behind Severus and then trying to look especially innocent. "'m helping my friend. My mother knows!"

"I'm sure she does." Or, no, he was sure she didn't, because this little boy didn't have a pure-blood name, going by his letter, and that meant that Walburga Black would never ever let her oldest son and heir run around with him. Still, he put his finger to his lips, smiling. They were just boys. "I won't tell."

"Aces!" Sirius was satisfied. Totally getting away with this!