Credit: Vivian Zink/ABC Television Group © 2012 Disney Photo: April, Meredith, and Cristina on Grey's Anatomy Season 8, Episode 13

The Grey's Anatomy alternate reality episode (Season 8, Episode 13: "If/Then") is almost here, and we couldn't be more excited. What exactly is going to go down at bizzaro Seattle Grace? For those who can't wait to hear what it's like through the looking glass, we've gathered all of the spoilers about the episode right here.

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The premise: This episode is about what the Grey's world would have been like if Meredith's (Ellen Pompeo) mother, Ellis Grey (Kate Burton), never had Alzheimer's, and Meredith had a happy upbringing. Instead of turning out dark-and-twisty, in this universe Mer is bright-and-shiny.

Relationship mash-up: As we can see in the sneak peek of the first ten minutes of the episode, the couples we know and love are nowhere to be found. Instead, Addison (Kate Walsh) and Derek (Patrick Dempsey) are still married, Meredith is newly engaged to Karev (Justin Chambers), Owen (Kevin McKidd) and Callie (Sara Ramirez) are married with kids (we won't be told what Arizona's [Jessica Capshaw] love life is like), and Ellis married Richard (James Pickens Jr.) (He's the loving father who gave Mer a stable home).

Relationship woes: These alternate parings aren't all smiles and fluffy bunnies. Shonda Rhimes calls Owen and Callie's relationship "the largest mistake of both of their lives." Meanwhile, in the first ten minutes we see Addison is expecting, but while the hospital staff thinks the Addison/Derek relationship is perfect, Kate Walsh warns that the audience will see "what's really transpiring." There's certainly tension between them in this sneak peek.

Lexie the...drug addict?: As we see in the first ten minutes, Lexie (Chyler Leigh) isn't a successful doctor in this world — she's a patient, in the ER for OD-ing!

Other character changes: In this world, Bailey (Chanda Wilson) is meek and unable to stand up for herself, Arizona is a tough doctor who butts heads with Callie, April (Sarah Drew) might be pregnant, Alex is no longer broody, Cristina (Sandra Oh) is a loner without Mer as her friend, and Derek is a bit of a slacker.

Returning faces: We will see some old faces, including Charles, from Mercy West.  However, we won't see George or Izzie. Sorry guys!

Are you excited yet?

Remember to tune in to the episode on Thursday, February 2, at 9 pm ET/PT on ABC.

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