'Grey's Anatomy': 11 Big Developments From the Season 11 Premiere

Adam Taylor/ABC

"Grey's Anatomy"

[Warning: This story contains spoilers from the season 11 premiere of ABC'sGrey's Anatomy, "I Must Have Lost it on the Wind."]

Grey's Anatomyreturned for its11thseason Thursday to kick off its new slot as the anchor of ABC's #TGITShondaRhimesblock with an action-packed hour that opened the post-Sandra Ohchapter of the veteran medical drama.

The fast-paced episode set up friction between Meredith and half-sister Maggie, brought Amelia into the Grey family drama and set the stage for a season of conflict between the board as they look to replace Cristina's seat.

Here are the 11 biggest developments from the season premiere.

Photos: 'Grey's Anatomy' Cast, Creators Say Farewell to Sandra Oh

1. A flashback seems to reveal Ellis Grey giving birth to baby Maggie before she moved from Boston to Seattle.

2. Richard (James PickensJr.) retreats to AA to share the secret of his long-lost daughter, Maggie Pierce (KellyMcCreary). And Amelia (CaterinaScorsone) happens to be at the same meeting to learn his secret. Amelia also has a secret one that she hasn't yet told big brother Derek (Patrick Dempsey).

3. Speaking of secrets, Maggie officially meets half sister Meredith (Ellen Pompeo), who has no idea that she's her half sister. To summarize Mer's feelings about her new colleague: "Pierce is no Yang, she's perky and chatty. I bet she likes cats."Dramaaaaaa! (And tequila!)

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'Grey's Anatomy': 11 Big Developments From the Season 11 Premiere