Succubats are corrupting parasites. They basically rewire people to feel good about helping demonkind, and bad when demonkind is harmed. So you have the same person, but one who thinks like, making someone else into a host is helping not only demonkind, but the potential host as well.

Like it messes with brain chemicals to make them love their hive and queen, but indirectly enough that like, each succubat host kind of filters those feelings through their own personality.