8. Source of Brock's Poisoning Revealed
The mind-blowing twist at the end of the fourth season was that it was in fact Walt who had poisoned young Brock with the Lily of the Valley, a plot strand that is sure to percolate throughout this final season, likely to explode in one of the final episodes. With Walt's frequent manipulation of Jesse - also including watching Jane overdose rather than trying to assist her - it is a giant elephant in the room, and something that will make for a grand reveal, as well as an emotionally fraught situation for sure. What Jesse will do with the situation is anyone's guess - could this be the information that drives him to kill Walt? If anything, it should make him realise that, in most ways, Walt is a far more savage and callous man than he ever has been.