What if Ellis Grey had not been stricken with Alzheimer's?

That would make Meredith Grey a much different person, clearly, and a lot less dark and twisty. This hypothetical scenario is the basis for the much-hyped alternate reality episode of Grey's Anatomy February 2.

In the aptly-titled "If/Then," Meredith dreams of a world in which her mother never had Alzheimer's and in which she had loving and supportive parents instead of growing up without her father, Thatcher.

This causes Meredith to be happy, which causes Seattle Grace to be completely different in every conceivable way. Couples you never imagined are together, while almost all the doctors have different hair!

For visuals of some of the many examples, check out our gallery of "If/Then" photos if you haven't seen it. Check check out ABC's first promo for the most buzz-worthy installment of the season below:

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.