ANo. Both have the same basic premise of fairy tale characters living in the modern world but they are otherwise unconnected. Fables was about a group of characters who flee their homelands and end up in New York City where they have been living for centuries. Immortal, and fully self aware, their attitude tends to be more cynical than the characters on Once Upon a Time. The show Once Upon a Time deals with fairy tale characters who are trapped in small town Storybrooke Maine after a curse from the Evil Queen brings them here. They are, mostly, mortal and are, mostly unaware of their true identities at the beginning of the series. While the two series share some characters, such as Snow White and Prince Charming, their depictions of these characters are wildly different. For example, in Fables, Prince Charming is something of a smarmy womanizer and politician. In Once Upon a Time the same character is actually charming, a devoted husband, and a great warrior but a poor politician.