Gilbert still wasn't saying anything, but Zach hoped he wold feel relaxed enough to talk, and perhaps something would peak his interest. Merlin knew Zach loved talking about just about anything really. Even charms work, and Zach did like his work. And Romilda was likely to find some aspects of it entertaining - maybe the story about his horns? Or would that make him uncomfortable?
When the voice came in, Zach didn't have to look up to recognize it. He didn't really know Hestia Jones, but he made a point of getting to know the voice of anyone who stopped by, even once, not to mention loads more. It helped him have context for bits of conversations he overheard. "Hello," Zach smiled, "Do stay!" Zach had noticed the two talking while flipping through his journal, and it made him happy to see Gilbert socializing.