"As far as everyone is concerned," Casimir began, "Your lackeys, and especially you, are nothing more than Slytherins bound to worsen the reputation of our house. I may do what I do, even give some people a few dangerous suspicions, but at least what I do is turned against people who actually deserve it. You on the other hand, you misuse your methods simply for entertainment. I may have helped you in the past, even congratulated you, but you're beginning to overstep your boundaries as you devolve into nothing more than another cheat."
Casimir had to admit that his response would probably do nothing to faze Acacia. Depsite being older than her, Acacia had a bit more skill with scathing or manipulative words than he did, probably as a result of her frequent use of such things. He looked over to the auror she had pointed out. It could be that he was from the Ministry of Magic, or maybe he was simply a new teacher here. Either way, he didn't care much one way or the other. Casimir was however, a little concerned about being accused of practicing the Dark Arts. It honestly wouldn't take much to do so, and knowing Acacia, she probably could pull such a thing off if she wanted to. But still, did it truly matter to him? He was actually going to start studying such an Art in secret with Artemis, and by technicality the Dark Arts weren't necessarily punishable by law, except in some cases.
"Now then," Casimir started again as he took a glance at Willow, "So long as you don't continue to prey on and use Willow, and anyone like her for that matter, you'll hear nothing from me. If you continue to do so, however, and end up hurting her in any way... I guess you can say you'll have a nice, solid reason to accuse me of dark magical practice after I show you why my spells have often been the subject of concern for some of the teachers here."
Casimir looked to Acacia, then to her lackeys, and then to anyone else who was either listening in or had been poking fun at Willow earlier. He smiled before sitting down, not wishing to continue on the argument with the girl. He hoped he didn't give off any... interesting vibes there. He didn't need his whole house thinking he had an interest in Willow. He was simply concerned for her, especially since he had already seen first hand just how unstable she could be, and before heard countless hurtful things said about her. Now she had Acacia on her back, planning to do God knows what by gaining her trust and using her. When was this damned feast going to start? He needed to get his mind off this stuff.