And despite the hard times that they’re facing right now, Regulus finds it within himself to roll his eyes and smirk, "You’ve always been bad at getting your homework done on time." Regulus went through so many bad things in his childhood and it always astounded James that he was able to find himself once again once he was in a better place, mentally, and that he still was able to joke and smile around James--obviously once the Gryffindor was able to break down his walls. There is no doubt that he, of all people, will find a way to tease or mess with James right now.