The group surrounding Bellatrix Black caught Severus's eye on his first day at Hogwarts. They sprawled over the real chairs of the common room, smirking and sneering as the new first years filed past. Bellatrix was their undisputed leader. If she turned her fierce eyes onto any of them they would freeze, trying to figure out what they had done to anger her and how to placate her before she turned her wand on them. Despite her beauty (and she was beautiful) Severus was terrified of her even as he was drawn to the group she commanded.
Years later, after Severus had finally gained access to the coolest of groups, he would curse his younger self, and long for the group of two he had formed with Lily.