It seemed that Cassandra was fascinated by Lyren's Dark Make. It was pretty cool in his opinion, especially it if was ones first time seeing dark energy. When the girl mentioned trying it and conjured up a Dark Blade of her own, all the color drained from his face. Almost every single one of the dark mages he had met were insane, it was what dark energy did to one's mind. It corrupted the spirit and ate away at a person until there was nothing left but a mindless killing machine. Some, like his father, could resist it naturally. But he had literally watched the dark energy eat away at his own father's mind. The only reason he wasn't insane himself was because of the magic rune on his chest. Which would only work within six months of birth.
It was then that he remembered what the Guildmaster had said before. She had illusion magic. And the horror turned into anger. The Dark Blade in his hand disappeared as he let the dark energy disappear harmlessly "Dark magic will literally destroy a person from the inside out, steal their sanity, their personality, until nothing is left but a mindless killer. Don't you dare ever joke about it like that again." He said, his voice nothing but a low hiss. He could usually take a joke pretty well. But not when it involved dark magic, especially when a person was naive about it.
One of the mages from earlier, Kai, started yelling something. About welcoming the new members to the guild. He found it hard to feel happy about that with the anger towards Cassandra. But instead of taking it out on her, he turned his attention to Kai, not wanting to hurt anyone with his temper. He wasn't exactly hungry at the moment, but he though it would be rude to not take some. So after a moment, he went over to Kai like all the others were doing. Purposefully ignoring Cassandra for the moment. At least until his anger settled down. He hated his temper, it was yet another gift from his father. But he was doing his best to not take it out on anyone.