For a few more minutes, he probed the air around them, took in the rising emotions. Then he slowly started to weave a spell. This would take time. Tom had taught him enough about parsel-magic to know how to make modifications to suit changed circumstances. While at Hogwarts, it was easy to pull energy. Here it was more important for Harry to amplify what was available. Luna had thoroughly enjoyed herself once, and it had given Blaise enough of a boost to get worked up himself. He had pulled the slight Ravenclaw into his arms, and she was riding him. Was it okay to watch? Hermione would be mortified, but Blaise had no such qualms. Luna didn't seem to care either. He tried to time his casting. To make the most of the energy provided. Harry realised that he was enjoying himself, as well. Did he have voyeuristic tendencies? Was that bad? Or did he imagine himself in Luna's position, maybe with a fair-skinned, dark-haired partner? Did he really want that, or did he want it only because Severus desired him? Did that even matter?