To be honest, Roderick's words weren't what gave Kaan the idea. Let's be real—Roderick was hardly persuasive enough for that.
Sure, his rambling had been motivational in the way that watching someone trip over their own feet is inspiring, but Kaan had already started considering the idea the moment he sensed the forbidden magic aura clinging to Eira like a bad perfume.
For some reason, Thessara seemed very interested in it. And, more importantly, someone in Eira had actually dared to mess with it. Apparently, forbidden magic had enough of a wow factor that, despite the very clear laws against it, plenty of vampires still couldn't resist poking the forbidden.
Kaan never intended to rely on it completely. No, this was more of a safety net. A backup plan, a hidden card to play if the unexpected struck again. He had to be prepared. And if he could bend a demon to his will—make it his puppet—well, that would be truly spectacular.