There have been times when the writers have dropped the ball, or completely rewritten the legend so you never quite know what you're going to get. Much has been made on the Internet of the Robin/Marian/Sir Guy love triangle. For some strange reason I was always rooting for the most heinous Sir Guy. Partly, no doubt, because of the brilliant acting and nuances that Richard Armitage brought to the role. Partly, also I think, because there was so much more to Sir Guy in this version than just the Sheriff's lackey.
SPOILER ALERT below:
You may remember my fascination with backstory and all the history behind a person's action. Never was that more evident than in season three as Sir Guy's motivations and life history were revealed. I always suspected he was not all bad, some of his scenes with Marian in season one hinted at his social ineptitude. His obsession with her was at times creepy and others oddly sweet. He truly loved her. I knew there had to be a reason that he could so easily twist her kindness towards him as a proclamation of love. Of course, she manipulated his emotions for her own well-being so some of his confusion, and inability to keep up, stemmed from her actions.
Finally, in season three, his past is slowly revealed, a sister returns, the existence of a brother is discovered. All that he thought he knew about himself and the world around him might all be wrong. As we see how past events shaped his decisions, and he experiences the truth of those events, he is faced with decisions about his future. While he can never atone for all of the lives he took, he can now see how far-reaching and wrong his actions were. He will never be trusted, his redemption incomplete but he moves forward armed with better information and a desire to if not right some wrongs then at least minimize any future damage.
Sir Guy was always a tortured and troubled soul. That doesn't change but he no longer subscribed to the life path that misery loves company. Had his back-story not been revealed, I doubt the viewer would have accepted the changes that took place within him.
The following video from episode nine is long, fan-made compilation but was the episode in which Guy's transformation solidified.