They're true fans if they've read the book because if they liked the film so much, they'll want to read it and see the movie. True fans do both. It doesn't matter if you watched the movies first or books first. You're a true fan if you do both.
Complete strangers bonding over their childhood without knowing each other, it's not just a fandom. It's a family.
"My friend reminded me there's going to a new generation of girls that knows Emma Watson as Belle and not Hermione Granger... I cried..."