Marek could not even begin to summon interest in notebook collecting, but since he'd asked, he listened with one ear. He picked up another quill, and touched the tip of it. Nice and sharp.
"Yes, I'm a creature of habit," he said, tone a bit distant, as he wasn't entirely concentrating on the conversation. "And I have a habit of making people who hurt my sister disappear." He didn't really care if his threat was underestimated. If he had a reason to hurt Alec, he wouldn't be throwing hexes. There would be a sharp, poisoned object painfully breaking Alec's skin before he even knew what was happening, and it would be all over. Maybe he'd use the one that had a side effect of making dead skin leathery, and make a Back-Up Plan skin-bound notebook.
When he looked up, however, his expression was mostly unchanged. "Just for future reference."