So what makes this even more creepy, is that I do not remember writing it. Ever. but then one night I open my docs and its just sitting there in recently opened documents so a demon just put this on there but its spook spook day so its going up. Interpret it as you want.

"It hunts at night." The homeless man said, rocking back and forth in his jail cell, covered in blood. Voight had looked at the exhausted homicide detective skeptically.

"This is the witness? Dan I thought you said you had something real that would help us."

The older man just gazed at the disgruntled person in the cage.

"He's real." He rasped, something like fear in his voice, something that makes the team look at him with wariness and concern. "They both are."

The team doesn't get to ask what the senior detective means by 'they'. He just leaves and it's the last they ever hear from him.

"It hunts at night."

…

They find a suspect, and a body. They give chase to the suspect, to the nondescript person who runs out the back faster than lightning. They split up, then get split up some more, until they're all on their own, and they're all lost and the suspect is long gone.

Slowly the team finds each other. Slowly they regroup until only Halstead is missing, so they get in the cars and jump on the radio and drift around deserted streets trying to find the only person fast enough to catch up their unknown person of interest.

They find him screaming in the back of an alley, trembling and wide eyed and sobbing, fighting them as they try to calm him down, as they try to keep him from hurting himself, from hurting the paramedics who eventually show up.

He doesn't stop until Rhodes pumps a hefty amount of ketamine into his system and then he almost dies as his overloaded immune system reacts to it.

He seizes and codes and then comes back screaming again when he shouldn't be conscious, and its all the team can do to walk out of the hospital to find the guy who did this to him, because if the best doctors in Chicago can't help him, then at the very least, Intelligence will find the man who killed their friend.

…

It's been two days and Jay is worse than he's ever been. The team is split, exhausted, and hopeless. Will is sitting numb by his brother's bedside, gripping his hand as Jay wails and bucks against invisible terrors.

Erin sits in front of the mans jail cell, who gazes back at her and knows there was another victim without her saying a thing.

"How do I stop it?"

"It comes at night."

"How do I stop it?!"

"It comes at night. Never the day. Always awake, never asleep. Always alone, never together."

She blinks.

"Why is it here?"

"Because we were careless. We thought we could forget it."

It clicks.

She gives him ten dollars in bus money and lets him out of the cell without another word.

….

"It's a nightmare." She tells Will, still empty, still hopeless as her partners vitals drop steadily, as his fever climbs as he gets weaker.

"What?"

"It's a nightmare." She repeats then drops a syringe filled with epinephrine into his lap.

"Wake him up."

…

Its two weeks before Jay responds to stimulus again. Another four before he talks. Two months before Charles tells Will he can go home. Six months, before Jay will meet with the team.

A year before he goes back to work. Three and a half before he starts to look them in the eye again.

They never catch who it was. They publish a finding, describe symptoms and how to treat a person, and spread it to all the hospitals in major cities, they show it nurses, put it online, ask scientists to investigate it. Its a substance, it has to be, but it doesn't combine like anything known on the streets. It's impossible to pinpoint. Cases pop up of unsolved deaths that match the same symptoms and conditions. Over three hundred people across the country, in the last ten years.

Jay's case saves another two hundred people in the following time span. People are traumatized, catatonic, never the same, but they survive. It takes time, but some people grow afterwards. Some commit suicide or turn to drugs. Nobody talks about what it's like. Ever.

Somebody gets a sample of the compound. It's liquid, not powder, and the chemicals disturb the natural balance found in the brain. Nobody knows what it shows people, what it does to them.

Sometimes, when Erin wakes in the middle of the night to see Jay curled on the floor in the corner, rocking back and forth with his knees to his chest, she thinks of what she might've blamed it on if she believed in god. She thinks, with absolute certainty as her husband stares at a space right behind her with pure terror, that is doesn't matter.

"It hunts at night." Jay whispers.

Erin believes him.

HAPPY HALLOWEEN!