Regulus was pretty certain he had stopped breathing for an entire minute, because he had never expected that Severus would actually kiss him back again. Warmth flooded his body, cutting through the cold that the rain had left. He pressed in closer the moment that Severus actually responded. One of his feet edged along the inside of Severus' and his chest was suddenly flush against the others. Maybe it was too much contact, but Severus could push him away if he needed to. His fingers tightened a little against Severus' neck as his other hand moved up to brush gently against Severus' cheek.
Regulus was simply too caught up in what was happening, in the heat that was curling in the lower stomach and the new angles, unexplored angles of Severus' face. He had thought about this for quite some time, but hadn't ever expected to get the chance to do it at length. He had always thought that it would only be stolen kisses, taken just days before he had decided to go and die.
He deepened the kiss, curling his tongue and running it delicately along the seam of Severus' lips. He knew that he was good at this. He knew that he was very good at this. He had spent so much time, more time than he really cared to admit, practicing and learning from James Potter. That was hardly something that he was about to confess to Severus, but he knew that he could drive James crazy and he knew that he could do it within a matter of seconds. He could show Severus that he was good at this - that he could make him enjoy it.