Personally, I think there are 3 possibilities.
1) Archie/Jiminy. Who knows more about what Reggie is feeling and needing these days than Archie? All the more reason for Cora to want to seek him out and get information. Taking his heart would allow her to do exactly that. She wants to control Reggie and having this information would be invaluable to her.
2) Marco/Gepetto. He has already betrayed the family once by forcing Blue to allow Pino to go through the wardrobe. Can’t imagine how upset he would be to finally be reunited with Pino only to have him turned back to wood. That could certainly trigger him off. Perhaps Cora made certain promises about restoring Pino back to real life to him.
3) Red/Ruby. Not sure why or what the connection is other than reading this spoiler from vancityfilming. Seems like something may be up between Red & Reggie. http://vancityfilming.com/articles/once-upon-a-time-october-25/
Keeper of Pandora's Box & The Yellow Brick Road.