While Severus might have wanted to return to his own place and time, that was the farthest thing from Regulus' mind. He was alive and, as far as he knew, he wasn't being hunted down to receive punishment for the things he'd done. It made him nervous that James Potter's grandson apparently knew everything, that so many other people apparently knew as well. That would certainly not work in his favor if the wrong people were to appear here.
Granted, perhaps Severus himself was running some kind of elaborate ruse in the hopes of turning Regulus over to Voldemort... but Severus had never seemed like the type to play games of this sort. If Severus wanted him dead or to deliver him to someone who wanted him dead, the younger Black was fairly certain he would already have a wand pointed at his chest. He cast a sideways glance at Severus that one might have mistaken for mistrusting, but it was gone as quickly as it appeared. No, Regulus was pretty sure that Severus was on the up and up.
He took another drink, draining his glass, and took note of all the different bottles of alcohol on display behind the bar. He wondered what they tasted like. "Do you think those are very different from the ones back home?" he asked, gesturing to the bottles. "Maybe we should find out." The corner of Regulus' mouth quirked up in a grin. He'd make this fun if it killed him. He wanted to forget everything else.