This Sunday on Once Upon a Time, Regina will have something in common with ABC counterpart Emily Thorne: she'll be all about revenge.

The series, meanwhile, will treat viewers to a unique rewind on "Welcome to Storybrooke," taking us back to when the curse first hit in 1983 and giving us a glimpse at when Mary Margaret first lay eyes on a comatose David. Watch the scene now for yourself:

In present day, meanwhile, Regina will set her sights on her new sworn enemy. In this sneak peek, she tells Gold all about it, as the two bond over Cora's dead body:

Finally, check out the following clip to see Gold then take this warning and pass it along to Emma and company. Will he stand up and defend Mary Margaret? He is known for repaying his debts, after all...

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.