"Stop it," he finally managed, voice shaking a little.

... he probably should have asked ZEX to stop a while ago. Sometime before his face started to burn, like when ZEX first mentioned interspecies lovers (which Zelnick couldn't protest too loudly, there had been Talana, but the Syreen were so close to humans anyway), or the first time ZEX had called him "love" or "my".

"... I don't think I'm interested in teaching what you want to learn," Zelnick choked out after a pause, feeling like a supernova had gone off under his skin; he didn't trust his voice further than that, right now.