As weird as the relationship might have been, it appeared to be clear in season two that Doug has unrequited romantic feelings towards Rachel. Even after his recovery he seemed to be more obsessed with her than ever before, and it honestly wasn't that surprising when he chose to spare her life. What was surprising was when he went after her moments later and the screen cut to him burying the poor girl. This completely changed the third season. Looking back on it, his desperation to find her may have been more out of revenge than love, something which could offer an entirely different perspective on the events leading up to that fateful act. Whether or not he always intended to kill her made the deed no less shocking, and the revelation that it was Frank who had sent Doug after Rachel to murder her - a fact which was nonchalantly discussed between the two - was another surprise.
