What does Regina get from holding Belle?

[Arjay369]

Now that her plan to poison Emma has failed and Henry is the one suffering the consequences, Regina will probably deal her trump card Belle to get Gold's help.

My thoughts exactly.

Expect the unexpected, Accept the unaccepted.

[Possum Snoodle]

For "insurance," I'd say. Regina seems to have inherited many traits/habits/abilities from her Mother and holding a person for insurance may be a lesson she picked up from experience. More precisely, from the incident of her Father being held "for insurance."

...POSSIBLE SPOILER AHEAD...

That whole heart-stealing-and-crushing power Regina gets from her Mother (I suppose) leads me to believe her Mother may end up being -- The Queen of Hearts. The similarities of Regina's heart vault and that of the one in the QofH's labyrinth in Wonderland/Hat Trick Episode are worth noting as possible connections to some kind of a relationship and history. Regina's comments of being "all too familiar with" the certain effects of the mushroom means she has used/seen what [that stuff] can do. Then, she also quipped "she [QofH] sees me as some kind of a threat.".

[Khaleesi]

Mr. Gold is going to teach people a lesson and make sure they remember. Don't ever threaten him with the people he loves. The guy is not someone you want to mess up with.

[charming]

If Regina expects to get a lot out of holding Belle she needs to find a way of negating the please clause. That is the only thing that Regina from having an advantage over Rumple because with one please everything she has planned can be undone. She needs to play it smart and I believe that was something Gold has been suggesting to her all season with every deal they have made. It should have been crysyal clear after the failure to frame MM for "Kath's murder". That was clearly a hint and a half without spelling it out for her, unless she is really thick.