: Martin Henderson joined the cast as Dr. Nathan Riggs, whose arrival triggers a dark history for Owen Hunt involving his missing sister.
'Grey's Anatomy' Season 12 Trailer: "Everything Has Changed"
: Their developing romance culminates in a wedding in the season finale, though Amelia initially has doubts and runs away before the ceremony. Greys Anatomy - Season 12
: This season marked the final regular appearance of Sara Ramirez as Callie Torres. Reception & Ratings
: Miranda Bailey successfully campaigns to become the hospital’s first female Chief of Surgery . : Martin Henderson joined the cast as Dr
: Meredith Grey adjusts to life as a widow, moving back into her mother's house with her "sisters," Maggie Pierce and Amelia Shepherd. A major mid-season arc involves Meredith being brutally attacked by a patient, leading to a long recovery and therapy.
: Alex proposes multiple times, but Jo repeatedly declines because she is secretly still married to an abusive man she fled years prior. Cast Transitions : This season marked the final regular appearance
: Jason George (Ben Warren) was promoted to a series regular. Giacomo Gianniotti (Andrew DeLuca) also became a regular mid-season.