Project a strong feeling of happiness in others
It was Didyme, Aro's sister, who 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.
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
Didyme showed this power even in human form, though it was much more dormant before she became immortal.
Though effective, the power has a side effect that leaves people without it in a state of negative emotions