I always though it was because Max needed to look into Liz's eyes when he healed her in the Pilot - he said she needed to look at him and thus we ended up with visions regarding Liz's side, probably because she opened her mind to him completely. Max then reversed the connection afterward, opening his mind to her to let her see the visions. Max never needed to look into anyone else's eyes (that we saw) when he was healing Kyle (he was out of it at the time) or the kids (it took more out of him because he was healing more than one person).
I think Michael, Isabel and Tess had a small part of healing for superficals stuff - Riverdog either broke or sprained his ankle. I can't remember if we ever saw Isabel heal and Tess healed Max's cut. Max was the only one out of the group who could heal major wounds probably because that was one of his main power as a king and the shield for protection. (they probably didn't want to overload and decided to give them a balanced group).
I think Ava saying Max changed Liz when he healed her was regarding him choosing her as his queen. In Season 1, Tess said Max wasn't dead because she could feel it if he had died yet in season 3 Liz was the one who felt Max die (Tess was still alive at the time). So future Max was wrong the entire time - it is possible that in his timeline - his Liz never had the chance to develop her powers or it was because Liz never actually found out that Max had changed her when he healed her (which probably got Liz to thinking as proven when Max came back from New York to see Liz checking for changes in the mirror). If you don't know about something, you don't think about it or see if it is a possibility. It probably never occured to anyone that Max had changed Liz when he healed her - they all just assumed that it was a normal healing (providing Max and Liz never actually said anything about the visions they shared as Max had a hard time telling Michael and Isabel about the visions that he got when he and Liz were in major make out mode - Sexual Healing). Nasedo probably thought he kissed differently from Max when Liz yanked away from him as he never actually said or at least spoke to Max regarding any flashes he got from Liz (but then again, he probably knew Max would have his head if he actually did confirm that he kissed Liz).
I felt the whole Cadmium X could have been explained more. I thought at least Liz would have been far more interested that it was a result of the aliens using their abilities. Surely she would have at least wondered if she had Cadmium X inside of her due to Max healing her because - at that time - it was a result of increased energy (Michael killing someone for the first time, Max healing someone for the first time). I would have liked them to expand it a bit more. Was Pierce's body the only time they ever encountered Cadmium X or did Nasecdo's victims have Cadmium X? Was it a result of someone dying due to alien abilities or could it have occured if someone had been healed using alien abilities. (Even in the books it's never explained - very annoying!)
To Kyle having powers - if we use the books which were an add on to explain the trip the gang took after the Liz got the visions of the gang being killed - Kyle actually gained powers but due to a major outlet in which helped them to finish of the skins - Liz and Kyle stopped having powers. It is possible people used that as a reference but because not everyone reads the books - it can be considered as not canon (considering one of them had Alex in the books but Tess had betrayed everyone - think she was working for the FBI at the time). I don't remember if Jim actually got any abilities. I think it was assumed that Kyle would get abilities because he had been shot just like Liz had been.
*phew and winces when she sees the post...*
Man, I have got to STOP with the long posts! Seriously.
I hope this actually makes sense - if not, let me know and I'll try my hardest to make it clearer.
![Very Happy :D](./images/smilies/icon_biggrin.gif)