It was Shepherd against Shepherd on Grey's Anatomy Season 11 Episode 7, as Amelia's past came back to haunt her and Derek didn't exactly fight for his sister's position at the hospital.
Yes, Derek eventually came around, but not before he got into again with Meredith.
Viewers can expect another blowout between Mer and Der on Grey's Anatomy Season 11 Episode 8, as they clash over the best way to handle a patient's case.
But the crux of the winter finale will center around another couple, as teased in the scary preview above.
The official ABC synopsis reads that Callie will “feel responsible when one of her veterans is pushed too far” and that “one doctor's routine procedure results in a devastating diagnosis."
It's clear that diagnosis will have something to do with Jackson and Avery's child. And we're afraid to even guess what it could be.
Check out the network promo above, watch Grey's Anatomy online if you need to catch up before next Thursday and go back in time with the cast here: