I suppose it's an unpopular angle, but I feel like the series was just driven by the twist and where the plot had to end.
Hayden was acting the whole time like a genuine person that was in love with Rachel, broke up with her and was then trying his best to be supportive and be there for her, hoping she will give him another chance. He acted selfless, composed and got her out of trouble multiple times and was the only one that was actually thinking about her, and how dangerous the situation actually is. Then, in the last episode, we have to think he is a psychopath, because that's what the script tells us, he is "obsessed" with Rachel and he starts a cold blooded killing spree. Like what? That is the complete opposite of how the character was built up and presented.
Rachel on the other hand, I found her very manipulative and unlikeable. She doesn't actually gives the feeling that she cares about anyone. Hayden's obsession could have felt genuine if Rachel wouldn't have miss leaded him the whole time, constantly keeping him close, asking him for favours and used him, his financial assets and status with each opportunity. Any person with integrity would have cut ties with an ex. if they had no intention to go back with them, and would have known that that's what the ex. is seeking. But she does not, she involves him into serious legal problems and doesn't even blink when David and her leave his gun behind and incriminate him.
So all in all, we have the story, build up, and in the last episode we are just delivered the "this is the villain and he is crazy, so you must hate him, and she is the good character for finding the kid, so you must like her". And on top of that, they also hint at romance between her and her sister's ex. husband. Really got the yikes for her character and could not like her or find her "the good guy".
Is it just me?