In its natural form, Serotonin is a roughly human-sized distortion in the air, nearly invisible, odorless, and silent. When Serotonin possesses a person, it alters the person's eyes so that the coloration in their iris fades, resulting in abnormally pale eyes. People will probably encounter it while it has possessed a scientist.
Serotonin is sent into the world in the midst of the creation and use of drugs. Scientists working for large pharmaceutical companies often create experimental drugs and study them on small rodents. These drugs are usually unknown factors in otherwise controlled situations. The creation of these drugs, especially when done by accident or with untested chemicals, creates an Infrastructure for Serotonin to enter the world.
Serotonin does not have a specific human form — it needs to be mobile, which means it can't get locked down. It most often possesses someone who has already been working for a drug company for years and has some kind of seniority. The God-Machine's disease is already at hand for Serotonin, it just has to get it into circulation.
Creating a need for the drug takes some creativity. Just like Vitamin D is added to milk and Iodine is added to table salt to prevent well known deficiency diseases, Serotonin worked to have the drug added to a commonly used staple in response to an artificial requirement.
Serotonin has an austere and clinical mindset. It makes a plan and sticks with it; its biggest weakness is its inability to adapt quickly to change. It picks a person to take over and uses that body's clout and station to get most everything done.
Success of the mission depends on Serotonin's ability to maintain the personality it is mimicking. Revealing Serotonin as an imposter is the fastest way to hinder its work. It is also the fastest way to make it an enemy. For the most part, it will ignore anyone that isn't key to completing its mission. If it realizes that people know it is supernatural or an imposter, it will attempt to eliminate them. Serotonin is not as smart as the person it has impersonated and depends on its influence over the minds of others to fit in. It can be tricked into revealing itself if done in the right way.
Attributes: Power 8, Finesse 11, Resistance 10
Influence: Drugs 2, Disease 2
Numina: Aggressive Meme, Dement, Fate Sense, Host Jump, Implant Mission, Innocuous, Rapture
Manifestation: Discorporate, Possess, Reaching, Twilight Form
Max Essence: 25
Ban: Serotonin cannot use its Numina against anyone already infected with the disease.
Bane: The specific serotonin antagonist drug, ondansetron, injected at 5 cc; Tears