Matt spent the rest of the week trying something new.

Instead of scouring the city for dealers and information about the new drug, he started searching for victims instead. He followed ambulances and cop cars as they raced to the scenes of crimes; he scoped out hospitals and psychiatric facilities. He even visited morgues in the dead of night.

And he let his nose guide him.

If there was no sign of the drug, he moved on. But if there was a sign - if he picked up the tell-tale acrid sent of the mystery compound - he detailed the nature of the crime or the medical condition of the person affected.

And a pattern began to emerge - at least, according to Karen.

"There's a clear clustering of cases," she explained. The three of them - Matt, Karen and Foggy - were bent over a map of Hell's Kitchen laid out on the conference table in their office. She'd marked all known incidences of the drug on the map and coded them with coloured pins: green for self harm, red for aggression or violence, and blue for medical illness. "You first started coming across this drug along the pier. But then it moved inland. Margaret was dosed near Balsley Park, but then the next set of victims were south of 49th street."

Matt tried to visualise the spread of cases as Karen talked. He only ever viewed Hell's Kitchen from the street level - or more accurately, the rooftop level. The city to him was a vertical jungle, a labyrinth of towers and negative spaces spread out before him.

So he flipped that view 90 degrees, until he was looking down, the maze becoming an orderly grid. And he started to see the pattern. "It's almost a rectangle."

"Yes!" Karen replied. "I mean, apart from a few outliers, that's the way it's looking."

"Which means, the next set of cases will be in the vicinity of the convention centre." Matt's heart started pounding with anticipation. After weeks and weeks of fruitless searches and dead ends, he finally felt like he was on to something.

Until Foggy dumped a bucket of metaphorical cold water over his theory. "Or it could be further south, outside Hell's kitchen. Or west. Or somewhere completely random. We don't have enough information to make that call."

"Foggy's right," Karen said. "We need more data."

"More victims, you mean," Matt growled. "More innocent people being dosed against their will." He slapped his hands against the table in frustration and started pacing. "How long am I supposed to just stand around and catalogue all this without doing something."

"You are doing something," Foggy protested. "Because of all this cataloguing - as you call it - we're miles closer to solving this thing. And it is we, Matt. You're not in this alone."

It was true. While he was finding cases by hunting through the city at night, Karen and Foggy we're trawling through news reports and hitting up their sources in the police precinct and emergency departments.

Calina was helping too. She was using her considerable intellect and research skills to learn about biochemistry and something called pharmacodynamics in order to try to determine the nature of the drug.

Maybe it was time to bring the whole group together on this.

"We should continue this at my place tomorrow. Calina...she's, um, been working on this too."

He sensed Foggy and Karen exchange a look, but he didn't know how to interpret it. Were they apprehensive about spending time with an ex-Widow? Or were they looking forward to meeting her - Karen for the first time, and Foggy for the first time properly?

Either way, they agreed to his suggestion, and the plan was set for them all to reconvene at his place in 24 hours. And Matt was left to spend another night on the streets as a passive observer of the horrendous violation that was taking place in his city - reduced to logging the details of the crimes that he should be stopping.

He hated it.

Even though he understood the necessity, he still hated it.

And he wasn't the only one railing against the unfairness of their situation. When he landed on his rooftop past midnight, he found Calina pacing the shadowed concrete space.

And he was instantly concerned about what it meant. "Did you have a nightmare?" he asked. She hadn't had a bad dream - as far as he knew - all week. Not since the night he'd slept apart from her.

Since then, they'd shared the bed every night. There were no more shy invitations from her, or anxious deliberations on his part. It was just an unspoken arrangement - when he came home after patrolling, he stripped out of his Daredevil suit, put on a fresh t-shirt and sweats, and slid into his side of the bed.

She'd usually be awake, hovering on the edge of awareness, as if waiting for him to return before succumbing to sleep. And she usually succumbed pretty quickly once he was beside her.

As did he.

And they both slept soundly and peacefully through the night, neither plagued by nightmares or insomnia.

They would start the night on their respective sides of the bed, but when they woke in the morning, he was usually holding her, spooned up close behind her with his arm around her waist and one leg wedged between hers.

That was another unspoken thing they steered clear of discussing.

"No," Calina relied softly. "No nightmare."

"So what's wrong?" He took off his mask and smoothed down his hair. Then he sat beside her on the metal vent.

She shrugged. "I guess I was just feeling cooped up. I haven't left the apartment in seven days. I needed some air."

It was a reasonable explanation - God knows, he would be climbing the walls in her place. "I know it sucks. But its the safest option-"

"For how long?" There was a bite of anger in her voice. "How long am I supposed to hide away from the world?"

"You know Yelena and the other Widows are working on finding the people behind your reactivation. Once they do, you can go back to living your life. You-"

"No. I'm sick of this. I don't believe there's a threat in the city. Or if there is, its not sat outside our building waiting for me to walk out the front door."

"Okay," he said, not used to her sounding so agitated. Every night this week she'd greeted him with a home cooked meal and a smile. She'd asked about his day and updated him on her research into his problem. And selfishly, he'd accepted it all without thinking much about her problem.

He'd just enjoyed...playing house with her.

God, he could be such a inconsiderate bastard at times.

"I'm not keeping you hostage, Calina," he continued. "If you think its safe to start venturing outside - and if you think you're fit enough to handle what might come - then I'm not going to stop you."

She crossed her arms over her chest. "Why do you have to be so goddam...reasonable?"

Matt shrugged. "I guess its the lawyer in me."

She didn't laugh at his joke. She just sighed, and conceded his point about her fitness. "My knee and elbow are a lot better. But if I was forced to run right now - or defend myself - it wouldn't go well."

"So just give it a few more days. Rushing back into the world is not worth the risk. And even if its a relatively small risk, I'd feel better if you don't take it yet." He swallowed sharply, remembering the events of last Friday night. "I don't ever want to see you like that again. I hated it."

"I hated it too," she whispered.

He bumped his shoulder against hers and tried to make her smile. "And I'm not sure I could take you down a second time. You're a hell of a fighter."

She didn't smile. Instead, her arms tightened around her, as if she was struggling to hold herself together. "If it ever happens again, I won't take that chance."

The defeat in her voice scared him. "What do you mean?"

"There's a few minutes of awareness, before the serum takes hold. Before it fully drags you under. I'll use those minutes wisely."

His stomach fell at the meaning behind her words. "Calina..."

"I was under that control for most of my adult life, Matt. And I've seen what its like from the other side, as well. I won't ever let it happen again. I won't ever allow myself to become that...soulless killer again. I'll do whatever it takes to stop it. To...end it."

She turned away from him to gaze out over the cityscape. But he grabbed her by the shoulders and spun her around, the desperate panic he felt spilling from his lips. "No! Calina, no. Don't even think about that."

He moved his hands up to gently grasp her face."I will always find you, do you hear me?" he pleaded. "I will always find you, and I will always bring you back to yourself."

She tried to pull away, but he held her firmly. "Callie, please! Please, tell me you won't hurt yourself. Trust me to save you. Please."

She stopped resisting. And sighed. "Okay. Okay, Matt."

"Promise me."

"I promise."

It sounded like the truth. And her steady heartbeat made it seem like an honest pledge. But he knew he couldn't trust that when it came to Calina. For the first time in a long time, he wished he could see. He had the sense that if he could lock eyes with her, and stare into her soul, he would be able to find out the whether she was lying or not.

And he'd be able to convince her to trust him.

But that was an impossible wish. Instead, he took her hand and led her down the stairs into the apartment. And when they crawled into bed together, he didn't stick to his side of the mattress. He didn't keep his distance from her - because it felt like she was the one keeping him at arm's length tonight.

And he hated it. He had the irrational fear that she would disappear in the night, slip out of his life like an apparition.

So he fitted himself against her back and pulled her into the crook of his body with a strong arm around her waist.

"Matt?" she whispered, obviously confused at the break in their routine.

"Shhh," he whispered back. "Go to sleep."

He buried his nose in her hair and breathed in her scent...then held her as they both drifted off.

———

Calina smoothed the blanket on the back of the arm chair, and straightened the books on the coffee table. She bit her lip as she survey the apartment for anything else that was out of place.

She felt oddly nervous.

But it was better than the strange melancholy she'd been plagued with the last couple of days. The feeling of being trapped and helpless. The feeling that had led her to the rooftop last night, where she had confessed her contingency plan to Matt - the plan for if the worst ever happened again.

She hadn't made the decision lightly - which meant she wasn't sure she could keep the promise she'd made to Matt to not go through with it. But he'd sounded so desperate last night, so afraid for her, that she'd ended up telling him what he wanted to hear.

Maybe it was the Catholic in him - and his fear for her eternal soul if she took her own life. Or maybe it was his guilt speaking. He felt such a huge, misplaced sense of responsibility for everything that went wrong in this city - he was bound to feel responsible for her as well. And she would hate to add to his burden, but her fear of ending up under someone's control again trumped every other consideration.

That fear had been growing all week. Slowly creeping up on her at odd moment throughout the day, catching her off guard with feelings of panic and unease. She tried to chalk it up to cabin fever. She tried to convince herself that it would disappear once she was back to fighting fitness and out in the world again...

But she wasn't sure. It felt like the events of last Friday had broken something in her. Something that might never be fixed.

Luckily, she'd had a good distraction from those troubling thoughts - investigating Matt's mysterious drug. Which his friends were coming over to discuss.

Here.

Any minute now.

Hence the nerves.

Which, typically, Matt picked up on. She wondered what was giving her away. Was it her fluttering heart? Her shaky breaths. Or just some quirk of her neurochemistry. "Relax, Calina. They're not coming here to judge your cleaning skills. Believe me, they've seen this apartment in a much worse state."

"I know. I just..." want to make a good impression. Matt's friends were so important to him. She wanted them to like her. In fact, it felt vital that they like her.

Before she could finish her sentence, there was a knock at the door.

"Come in, guys," Matt called.

Foggy was the first to enter the living room, his wide smile not quite masking the wariness in his eyes. She didn't blame him; the last time he'd come through that door he'd found her locked in combat with his friend, the two of them bloodied and thrashing on the floor.

Then he'd helped restrain her.

She held up her hands and wriggled her fingers. "No handcuffs this time."

She'd been aiming for a joke. A way to lighten the mood and address the elephant in the room at the same time. But Foggy just frowned at her in confusion.

Matt jumped in to explain. "Um, Calina is still working on her jokes."

"Yeah," Calina said. "Sorry."

Foggy laughed and awkwardly patted her on the shoulder. "No problem. I just hope you're not taking humour lessons from Matt."

"Hey, I'm funny," Matt protested.

"Sure you are." The response came from the woman behind Foggy. "We laugh at you all the time."

The woman took a step closer to Calina and held out her hand. "Hi. I'm Karen."

Calina shook her hand "Calina. It's nice to finally meet you."

"Likewise."

Calina sized the other woman up. It was an ingrained habit - born of a lifetime of being pitted against other females - and one that she wished she could break. She wanted to be friends with Karen. She didn't want to see her as competition.

But as she assessed the other woman, she felt stirrings of...envy.

Karen Page was beautiful. She was tall - an inch or so taller than herself - with long, silky blond hair, and big blue eyes. But it wasn't her superficial looks that Calina coveted. It was the sense she got that Karen was comfortable in her own skin; the sense that she knew who she was, and moreover that she liked that person.

It was something that Calina struggled with on a daily basis.

She was also so comfortable around Matt and Foggy, which only added to Calina's sense of envy. She smiled freely around them and joked easily. She made herself at home in Matt's apartment, grabbing a glass of juice from the fridge before taking a seat at the dining table.

And when they moved on to discussing the mystery of the drug, she took the lead in summarising the case.

Calina stashed away her feelings of jealousy, and concentrated on the data being laid out. This was much more important than her petty insecurities. This drug was altering people's brain chemistry and making them act out of character - something she knew a thing or two about.

And something she'd been researching all week.

"I might have something," Calina said after Karen finished filling her in on the geographical spread of the cases. Matt raised his eyebrows in response. Foggy sat up straighter, and Karen smiled at her encouragingly.

"I don't think we're dealing with a drug in the conventional sense. I've been looking into why there's been no trace of a foreign compound in any of the victim's blood work."

"Our forensic toxicologist talked about that on the witness stand," Karen interjected. "He theorised that the current tandem mass spectrometry panels aren't calibrated for novel compounds."

"That's true. They can't tell you about the composition of novel drugs - but they should still register spikes for unknown compounds. And there was nothing in Margaret Posen's results to indicate there was anything in her system. The toxicology results for the other victims were clean too."

"So...?" Karen asked.

"So I started to ignore the toxicology." Calina shuffled through her papers, and pulled out several printed sheets that she'd highlighted earlier in the week. She laid them out on the table. "Instead I concentrated on the lab work for the victims admitted to hospital."

She pointed at the first page. "This is the CSF result for Steven Cho. He was admitted to Metropolitan General last week with a delirium-like episode. As part of his work up, they did a lumbar puncture and sampled his cerebrospinal fluid. They were looking for signs of meningitis to explain his symptoms, but found only increased levels of glucose, which they dismissed."

She moved on to the next page. "This is the urinalysis for Miriam Giles. She presented with extremely high blood pressure and a racing heart. They were suspicious for a type of adrenal tumour that can cause those symptoms, so they checked her urine looking for catecholamines. It was positive - but there was no tumour on her MRI scan."

Calina pointed to page after page showing abnormal results, explaining each one as she went. Then she summed it up. "In isolation, all of these abnormal results can be ignored. But I had the benefit of knowing that all these patients are linked. And when you know that, you start to understand what you're dealing with."

"Which is...?" Foggy asked, looking completely baffled.

"Fight or flight."

Matt leaned forward in his seat and cocked his head. "Fight or flight? You mean like an adrenaline surge?"

"Yes. The catecholamines that were in Miriam's urine were specifically epinephrine and norepinephrine - otherwise known as adrenaline and noradrenaline. It all fits - the increased glucose levels, the high heart rate-"

"But I would have detected the increased adrenaline on these people," Matt countered.

"Not necessarily. You've said it yourself - the smell of the compound is overwhelming. Maybe it's strong enough to mask the effects."

The three faces staring back at her still looked sceptical, so Calina continued to lay out her case. "It doesn't just explain the blood work - it explains all the different behaviours these people exhibited." She pointed to Karen's colour-coded map. "It's called fight or flight for a reason. How you respond to the stimulus of intense fear and anxiety depends on the type of person you are."

Karen nodded, suddenly seeing the threads linking the different cases. "So one person might respond by jumping off a building-"

"Taking the 'flight' part a bit too literally," Foggy commented.

Karen groaned and rolled her eyes. "Another person might try to fight it - turning their fear outwards."

"Like Margaret Posen," Matt chimed in. "She'd been pushed to the brink by the abuse of her ex-husband, and when faced with that fear again she snapped and fought back."

Calina nodded. "There's also research that suggests excessive adrenaline has similar effects to certain stimulants - causing paranoia, hallucinations, violence and unexpected physical strength."

"The hallucinations would explain why Margaret mistook an innocent women for a threat. And it would explain the behaviour of those thugs terrorising the bar."

"And then the last group - the ones whose bodies couldn't handle the effects. Their hearts give out under the strain or their blood vessels burst."

"Like the truck driver I came across," Matt added. "The autopsy result said he had a burst aneurysm in his brain."

"Holy shit," Foggy breathed. "It really does all fit."

"But why wasn't the adrenaline picked up on the drug screen," Karen asked.

"Because like I said at the start, we're not dealing with a conventional drug. There's no exogenous adrenaline in these people's systems. They're making their own adrenaline in response to something. Something that doesn't show up on blood tests or toxicology assays."

"What could do that?" Matt asked.

"Pheromones," Calina answered. "These people are being hit with fear pheromones. And its triggering a massive, mind-altering fight or flight response."