You know how the hands of the clock points to 21, isn't Joy 21 y.o...? It could be a fluke but there are many instances where Joy felt different than the rest...
Irene, Seulgi and Wendy were introduced through SM Rookies,
but Joy was never shown as a trainee and was introduced the first time through Red Velvet's teaser.
(Yeri was also introduced through SM Rookies as a trainee)
During Happiness, she's the only one with a jewel on her crown and a straight face
During ICC, she's the only one looking back and also has a different hair color
During Dumb Dumb, Joy is the only one having both her feet on the ground
I don't have a picture, but in One of These Nights' video, she was the only one who survived, etc..
Like I said, it could be a fluke.. but that's just what I thought so please don't curse at me!!
original post: here