...okay, I'm now trying to picture some sort of scenario where Jane kisses Red John to keep him from leaving. (It actually almost works in my head, because in my mind, Red John fancies Jane, and if Jane saw that, he might be willing to play along if he thought it'd give him a chance to stay close to Red John long enough to get his hands on a weapon. And it's possible that Red John not-entirely-inaccurately read a certain degree of reciprocated interest in Jane's intense fixation on him, but he'd probably still be aware that Jane's basic plan was to kill him, and foil that in some way.)