The fact that he wants to be Vader and Rey learns that’s he’s afraid he’ll never be is one of the best parts of their respective characters. Ren’s flaws make him more interesting.
This was something truly incredible about Force Awakens. I absolutely loved Adam Drivers acting when she says “…that you’ll never be as powerful as Darth Vader”. In that moment he feels so violated and like she finally discovered his darkest secret. I’m excited to see this play out further in episode 8.
I would say that’s one of the best scenes in Star Wars period.