Leading up to episode 6 of Extant, we knew Molly’s baby “boy” wasn’t normal, but now it’s clear he is dangerous. Very dangerous.
At the beginning of “Nightmares,” the fetus (still sitting in a vat) compels an International Space Exploration Agency researcher to kill his colleague, after the former seemingly comes under its influence. He later tells ISEA director Alan Sparks that a former researcher named “Sarah” ordered him to commit the murder, and to liberate the fetus. My theory is that “Sarah” was really a vision/hallucination created by the fetus à la Molly’s Marcus sightings.