"Marcus's life changed dramatically when Aro brought home his newly turned younger sister, Didyme, along with the first members of the guard - vampires who were drawn to Didyme's aura of happiness. None of these early subordinates lasted more than a few centuries; they were still experimental at that point. Didyme's gift had always been with her, though subtler during her human years, and so she was used to many suitors."
Happiness induction is Didyme's raw ability to bring joy to oneself and everyone close to her or him.
Description
According to Stephenie Meyer, it was only shown by Didyme, Aro's younger sister, which made the Volturi members around her happy during her time of existence. But the most benefactor of this talent of hers was Marcus, one of the Volturi leaders, who became her mate. This power seemingly released an aura of happiness that naturally affected everyone around her wherever she went.
Happiness induction also can bring happiness to the beholder, as well as those around them. However, Jasper's emotional manipulation, can only control the emotions of others.
Corin's ability to make others content and happy with their situations, though it has a side effect. Anyone constantly exposed to her power will feel physically uneasy if they are not exposed to it for an extended length of time.
Jasper Hale's ability to manipulate others' emotions is in certain ways more powerful than Didyme's, because he can influence the emotions in any way he pleases. Like Didyme, his power only works while he is present.
Added by CrazyforCarlisle
