Betsy Monroe
Betsy Monroe was the other wife of Wayne Weinsider, a medical technician who harbored a dark secret: he was a demon. Wayne impregnated women and then killed them or killed the unborn child if the ultrasound showed signs of demonic features. This demon desired to conceive a child who was human but always seemed to be disappointed.
After the events around his wife Laura Weinsider, Wayne learned from Betsy Monroe that the ultrasound had revealed strange abnormalities: growths on the head and a deformation of the upper vertebrae.
Wayne drugged Betsy Monroe, as he had Laura Weinsider, with the intention of plucking the demon child from her womb. But as he appeared in his true form surrounded by fire and pulled Betsy towards him something unexpected happened.
"What are you doing, Wayne?"
An irritated and unshocked Betsy Monroe grabbed the demon by the throat as it reverted to its human form and said, "What are you doing Wayne?"
Betsy had the same secret. She was a demon. Not long after Wayne had realized what Betsy was, Mulder and Scully were on their way to apprehend Wayne Weinsider, having discovered the skeletons of infants in the backyard of the house he shared with his other wife Laura Weinsider, when they met Betsy Monroe speeding at them in a car. She came out of the car with blood all over the front of her clothes crying that Wayne took her baby. Scully, Mulder, and local law enforcement that included Laura's brother, Deputy Arky Stevens, arrived to confront Wayne Weinsider. They found him digging up the backyard of the home he shared with Betsy Monroe. He claimed Betsy Monroe wasn't like Laura before being shot by Laura's brother without warning.
In Betsy Monroe's backyard, Scully reports having found four infant skeletons, all normal and human in appearance.
Betsy Monroe, single mom and ancient demon. She's kind of a catch.
Betsy Monroe was a demoness who could only conceive human children until Wayne came along. Betsy Monroe is seen driving away with her newborn demon baby, that which she had most desired.