The Orphan is a villager that has to chose someone every night. Then they will "sleep" at their place.If one of them were to die or get healed both would experience it.
E.g. When the werewolf kills the target of the orphan, both the Orphan and the target would die. If the witch heals both will get healed.
The Orphan tilts the chances of winning towards the werewolves because there is a chance two will die.