There was no reason to study, nothing important was coming up and he was passing all his classes, but Regulus' desire to exceed all expectations had driven him to sit down afternoon and review his studies. Potions wasn't his worst class, he was actually amongst the high-ranking students of his year, but it was a subject in which he often got confused and had to backtrack his steps before continuing forward. It simply did not stick in his brain as easily as, say, Charms or Transfiguration. So he made a concerted effort to study a bit more for his Potions class, as to ensure that he continued in his rank. Furthermore, he often did his assignments early, if he could.
Seeing as it was Saturday and nearly everyone else had gone off to enjoy the weekend with their friends, Regulus had the common room to himself, more or less, and took advantage of the expansive space and assembled himself on one of the couches, books and papers strewn out around him. He was comfortable, feet pressed against the opposite armrest and his coat piled up behind his head as a makeshift pillow. One thing he hadn't expected was that someone would dare invade his personal space and privacy and, worse of it all, dare to insult his work.
Regulus sat up immediately at the voice and turned around to scowl at whoever that fool was.
Naturally, it was Slytherin's resident creep, Snape.
"I don't recall asking for your input," he seethed through clenched teeth, feeling ferociously defensive. Of course, the older boy's tone, insinuating that he was better, drove him mad; Regulus didn't take criticism well, particularly from someone he didn't admire in his obsessive way. But he wasn't quite ready to be downright cruel and disrespectful. Outside of the snark and egotism, he really didn't mind Severus Snape. Much.
He glanced back at his homework. Damn. Snape was right. This only enraged him further, and that, that was what had pushed him to say:
"Can't you find someone else to impose your presence upon? I know you haven't any friends, but I simply do not have the time to indulge in politely nodding my head to whatever nonsense you choose to rattle on about."
It really was unfair of Regulus, not to mention petty and childish, but it was such a natural reflex for him.