: Martin Henderson joined the cast as Dr. Nathan Riggs, whose arrival triggers a dark history for Owen Hunt involving his missing sister.
: 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. Greys Anatomy - Season 12
: A bitter custody battle over their daughter, Sofia, ensues when Callie plans to move to New York with Penny. : Martin Henderson joined the cast as Dr
: Alex proposes multiple times, but Jo repeatedly declines because she is secretly still married to an abusive man she fled years prior. Cast Transitions A major mid-season arc involves Meredith being brutally
: The couple's marriage collapses, leading to a divorce. However, they discover April is pregnant shortly before signing the papers.