That's kind of a noodle scratcher as far as Herc is concerned. The only Diana he knows is his half-sister, and they've never exactly seen eye to eye on most things. Admittedly that's most of them and Herc but her in particular. He nods in an "I'll do just that" sort of way because if he meets this Diana, he definitely will do that.

His expression changes immediately when Cass brings up her parentage, from thoughtful to something bright and happy. It wasn't that he'd intended to say anything about her being pretty, she was...but she was a touch young for him, he'd just not quite known where to fit her into his view of the world. That, though, makes her family.

"Then that would make you my half sister," he exclaims, actually grabbing her into a full armed hug, accompanied by a thunderous clap on the back. "Now that is a stroke of fortune!"