E.L.’s made a common writing mistake here. Remember: just because you know everything there is to know about, say, the meaning of the mysterious prophecy that came to your protagonist in a dream, that doesn’t mean you can give your characters that knowledge without a legitimate reason.
How did Ana know that the Greys rescued Christian or that he experienced his ‘profound hunger’ as a child? E.L. never showed Ana learning those things. A week ago, Ana didn’t even know who Christian was. Ana only knows this stuff because E.L. knows it and forgot, here, that she hadn’t revealed those details of Christian’s past yet.