"You will need professional help. Go to Confusion and find a man called Jacob Fulier. He's the best demon expert I have ever met. He'll be happy to help you."
- Solanum III, The High Priest of Orth about Jacob Fulier
He plays a central role in the "Demon Baby" quest.If the protagonist ask Jacob's help (after being told to do so by Solanum III), he will tell that the baby is really a demon child and must be killed, gives a Ritual Hatchet and explain how to do a gore ritual to kill the demon.
After the protagonist rescue Olaf and go back to your bunker, they will discover that the bunker people are gone resting only the dead "demon" baby in Emilia's room, killed apparently by the same ritual described by Jacob.
There is the option to take the baby's body to Jacob. If it is done, Jacob will then examine the body and praise the protagonist for perform a perfect killing ritual, even better than Jacob could do. After the protagonist tell that the baby was killed by somebody else, Jacob will comment that, whoever did it, knew what was doing - probably the Federation Army have demon hunters even more experienced than Jacob.
Jacob will pay $10000 to the protagonist for the baby's body, commenting that he know it worth more, but it's all the money he have.