[Anders]

Originally Posted by joppeknol

It is not known yet, but a human cannot survive without a soul. Since a soulless has no soul of its own, it needs to feed regularly on the souls of the people around him.

As a baby, it feeds on the soul of its parents. Later it feeds on his class-mates and friends. People who are fed upon don't die immediately but look less lively and more depressive. Parents of soulless look very tired (No one noticed that, because parents of babies often look tired.). Later they feed on several people at the same time so that the effect is less notable. You don't find anything wrong with a soulless itself. It's just that the people around him look tired and faded. They also often switch in their social environments and don't have long-lasting friendships or relationships.

Feeding on souls often works better when people are emotional. Causing Pain, anger, lust is a second nature to them. When you investigate their career paths you see that they always work at places where these emotions are exploited. In the end they have big conspiracies to cause more raw emotion in the world (Pick you favourite negative influence and let them be the ones behind it.)

You could go with the Gaudivore from Horror, which Afflicts Chronic Depression and Links it to Leech. Put this together with Draining (p. B1329) and you get someone who will lose HP unless they use their power. A less extreme gaudivore could simply make people feel down in the dumps - a quirk. Maybe long-term effects include Chronic Depression. Lifebane is another possibility.