I've just read GLRebirth #2 today, and it looks as though parallax is actually a seperate being to hal jordan. They refer to the impurity of the ring, and that 'it has a name' (parallax).
I think that's why kyle is unwilling to use his ring - he's afraid that it might take over him.
All of the other GL's that were using their rings look like they are going mad because of this impurity, but it looks like kyle will be the one to sort the mess out, as he hasnt used his ring since landing on earth.
I seems as though the impurity of the old GL corps rings is actually parallax, and is seperate from hal jordan (it took control of hal when coast city was destroyed)