Jace relaxed quite obviously at the reassurance, even if he didn't let himself react to the news about Alec being a submissive. That was a worry for later, when he could actually talk to Alec, see him, and make sure he was really alright. It also meant he could probably trust that their parabatai bond was working correctly, and he'd know if Alec was in danger. That alleviated a lot of Jace's current worries.

"Some of them are... passive?" Jace said, trying to describe it to Caliban. Some of them, like our healing rune, has to be activated when we want to use it. "Thanks. I'm pretty fond of them myself," he said wryly. He wasn't sure why he was being so chatty with the attractive man (and where the hell had THAT thought come from?), but he continued blithely. "The runes Alec and I give each other are the most powerful, because of our bond."