Chas looked toward John when he gave an answer for how he thought the link could be there. He had admit, he never would have thought of such a thing, but then that was why he wasn't the mage and John very much was. He then turned to Serena when she spoke up with more ideas for why this was all happening to the two of them and how it wasn't strictly two separate issues. The looking back and forth between Serena and John continued as they both threw out ideas back and forth for what would be causing such issues for the two women, deciding that although some of it was making sense to him, he was well and truly out of his depth with all of this. "What do you usually do to stop it when you get this shaky? You have any particular motions that you put into place?" Chas asked, knowing that if it was just simply a panic attack or anxiety, most people focused on taking deep breaths to slow down their heart rate which also means they stop themselves from passing out. So he wondered if Serena had that sort of thing in place or not, especially as she was a medical student for a while, and would have possibly learned such techniques to do in this kind of situation. 

"As for the other thing, is it possible that they know that there could be a link between their powers, or had a feeling they were meant to meet? Using Serena to find Kay basically?" He theorised in question. It was the only thing he could really think of for why demons and/or whatever else was after the girls would be going after the both of them by using one to get to the other. If Kay was awake, he wasn't so sure he would have expressed his theory out loud with her in the room, but seeing as she was asleep he didn't see the harm in expressing it out loud. Out of the two women, it was clear that Kay was learning all of this for the first time, whilst trying to accept she was very much part of the magical downworld, whereas Serena knows what she is and has done for years now. He would have felt bad if he overwhelemed Kay with all of this, especially with her head injury she sustained earlier on, trying to help Serena and save her.