OUAT creators Edward Kitsis and Adam Horowitz have hinted some more about Rumple and his son:
Are we going to see more of Rumplestilskin’s son?
EK: Yes. And you will understand what happened between them. I would say there is great stuff with Robert and the son, as to where it is–I would say not this season–perhaps.
AH: Or we might this season–perhaps. The character of Baelfire, Rumple’s son, does come back later this season, whether it’s in Storybrooke or in fairy tale land, how that plays out, we want to be a surprise.
EK: In other words, we want you to keep watching. [Laughs] http://www.buzzfocus.com/2012/03/25/once-upoon-a-time-showrunners-edward-kitsis-adam-horowitz-wondercon/
"That’s how you know you’ve really got a home. When you leave it, there’s this feeling that you can’t shake. You just miss it." Neal Cassidy