Once Upon a Time has lasted three seasons. I know how everything got to be the way it was with characters on the show. What if that was somehow undone; story-wise? That is what Hook and Emma do after falling through a portal that allows you travel back in time during the 3rd season finale. Emma, who at the start of this is set on leaving Storybrooke and even see her parents as just prince and princesses and not real people. One moment where Emma interrupted an attempt by Snow to steal something from Charming is how it starts to unravel. So the two have to go to Rumpelstiltskin for help. Just as Hook mention that it isn't a good idea for Rumpelstiltskin to see him of their history. Rumpelstiltskin showed up and agree with Hook on that.
Rumpelstiltskin does that kind of timing two more times during the season finale. One moment where he help them sneak in some palace to make sure Snow gets away with a ring that is a vital part of her parent’s romance. The other is when Rumpelstiltskin shows up just as Emma trying to get home through a portal and wanting to know more information about his son.
As for the way things play out or suppose to play for the Charmings, love will find a way and you can't beat fate come to mind. Plus Emma gets to see her parents as real people as their first meeting ends. As result, she also sees Storybrooke as home where at the start of the episode she didn't. Not a bad way for Once Upon a Time to do a what if.