April has "really changed," Rhimes emphasizes. Upon returning from her tour, she'll be "fighting for things to be better."

Viewers will finally see Stephanie's backstory. We'll also see Stephanie on the dating scene and we'll explore her dynamic at work with Amelia.

Jo will be in a rivalry as she fights "for what kind of doctor she wants to be and struggle with not being as good as Stephanie," says Rhimes.

Ben will find himself in an "awkward position in his marriage" with Bailey's race for chief getting intense, previews Rhimes.