The past few days have been rather traumatic for Sirius, but he was doing his best not to dwell on it, because he had a whole new London to get on with getting used to, a new life to start. Thank God Remus had been here and had somehow been the one to find him, because he wasn't sure what would have happened otherwise. He likely would have been arrested by the muggle police and probably even been declared insane, for he would have insisted it was 1981, not 2016.
Instead, he'd been taken to Moony's flat and been taken care of as well as caught up on this new reality he found himself in. A trip to the Ministry had gotten him further sorted, and while there was one more meeting he would need to undertake soon, he wasn't quite ready to meet the adult version of the infant he'd seen just a few nights ago in Hagrid's arms.
But at least he now had money in his pocket, and he knew just where he wanted to spend it. He'd always enjoyed muggle toys (which reminded him, he'd have to find a way to get a new motorbike, as he had no idea where his old one might be by now, and at any rate it was decades old even if he could locate it), and from what he'd seen so far of Remus' mobile phone, he knew he absolutely had to get one of his own.
Finding a shop to purchase one hadn't been difficult; he'd simply asked the first person he saw peering at their little screen where they'd got it and gone there. The problem now was that there were an awful lot of models and varieties to choose from, and he had no bloody clue what he was looking for, what made one version more or less desirable than the next. He wandered around the shop peering at the little cards that announced each phone's features (which may as well have been in Bulgarian for all the sense he could make of them), fighting the urge to just buy the most expensive one in the shop and be done with it, as he no longer had unlimited funds available, at least for the moment. "Which one do you like?" he asked a nearby person with a flash of his charming smile, not bothering to check if they were an employee or if he was simply hassling a random customer.
[Welcome to modern-day London, Padfoot! If your pup wouldn't have a reason to be inside a mobile phone store, feel free to run into him outside trying to figure out how to work his shiny new smartphone. :D)