One day Robin would ask himself how his shock had turned so easily to rage; why his first reaction was not disbelief at this betrayal but black, consuming hatred.
Beause at the end of the day you always knew she wasn't truly with you even if you tricked yourself into not seeing her true nature, into believing she was with you.
Letty is Robin's Evie. She is his true catalyst in this story, not Professor Lovell.
