BY THE TIME HOTCH ARRIVED, Katharine was thoroughly rattled. There was the matter of Dr. Nichols's dead body, which had its head beaten in and minimal bloodshed, thank God. Katharine wasn't sure she'd be able to keep herself from vomiting if the doctor had bled excessively. Though that did tell them that their unsub wasn't a killer at heart if his method of attack didn't give that away already.

Katharine once again told herself not to give Dr. Jemma Simmons a call but debated on dialing up Natasha's number for easy access to Dr. Banner or even Dr. Helen Cho, who had assisted them during the Ultron crisis. In the end, she decided she shouldn't outsource without Hotch's approval. After all, the general was still hanging around.

She had isolated herself to the lab area of Dr. Nichols's home, going through his things and trying to find out more about the unsub through the doctor. She could hear Spencer pacing closer to the windows, most likely anxiously awaiting some sort of backup.

And when backup did arrive, they stayed well away from the house. Spencer called her over to the sliding glass door and held his phone out in front of them, allowing Katharine to be a part of the phone conversation.

"Reid, Katharine," Hotch answered, looking at them through the glass.

"Hotch," Spencer said. "I really messed up this time."

"Reid, we need to get you out and to the hospital," Hotch told him as EMTs and what looked to be a cleanup crew swarmed the area around them.

"No. I'm staying right here," Spencer insisted.

"No, you're not, Reid," she heard Derek argue.

"I'm already exposed," the genius said. "It's not gonna do me any good to stop working the case."

Katharine watched as Whitworth approached Hotch and Derek, saying, "He's already infected. Now, if Nichols created the strain, he may have also created the cure."

"My best chance is to stay here, see if there's a cure, try to figure out who killed Dr. Nichols." Spencer nervously glanced over at Katharine. "And two sets of hands are better than one. I have Katharine in here helping me."

She saw Derek turn slightly toward Hotch. "Come on, Hotch, say something to him."

"He's right. His best chance is inside," the dark-haired man resigned. Then, addressing Spencer, he said, "We're gonna get a suit and mask into you right away."

Spencer shook his head once. "Don't bother. It's not gonna do me any good. I'm already infected."

He hung up and turned to Katharine, who couldn't help but feel concerned for the man.

She set her jaw and grabbed hold of his hand. Every instinct in Spencer's body seemed to tell him to take his hand away from hers, but he resisted. He gripped her hand tightly and closed his eyes, letting out a shuddering breath.

"Are you okay?" she asked softly, searching his face for any giveaway that the anthrax could be progressing faster than normal. He looked okay, for the time being, there was no telling how bad it could get from here.

"Yeah," he replied quietly. He opened his eyes and looked into her own, searching for maybe even a semblance of hope. When he found it, he squeezed her hand and let go. "C'mon, we've got work to do."

WHEN HOTCH CALLED THEM BACK, Spencer and Katharine had already gone through the entirety of the physical objects in the dead doctor's lab. Katharine was standing by what appeared to be Dr. Nichols's desk when Hotch called to ask for what they saw in the building.

"I see cages filled with dead animals," Spencer said. "I see signs of a struggle, probably before Dr. Nichols was murdered. Equipment's missing. There's a large desk. Clutter all over the surface. But in the corner, there's a smaller desk. It's organized, functional."

"Two different workspaces?" Derek asked.

Katharine made her way over to the secondary desk with a sample of Dr. Nichols's handwritten work. He looked between the two pages before answering Derek's question.

"Two sets of handwriting," Spencer compared the samples. "I'm looking at instructions on how to boil lab-grade broth, sterilize lab equipment, and transfer spores."

"Nichols would know all that," the general pointed out.

"He has a partner, maybe even a protege," Katharine deduced. "Go back to the BAU and try to figure out who this partner is."

There was a moment of silent debate on the other end of the phone before Derek finally spoke. "Hotch, why don't you go? I'll stay with Kat and Reid."

"Funnel all the information you get to me," Hotch ordered before hanging up once more, leaving Katharine and Spencer alone in the house once more.

THEY SEARCHED THE LAB PORTION OF THE HOUSE FOR A LITTLE WHILE LONGER, Katharine staying near Spencer in case he collapsed or something similar. She was worried, that much was obvious, but she tried not to let it show at every cough that he gave.

When they received news that Dr. Kimura was on-site, Katharine exhaled in relief. The sooner they got Spencer out of the house, the better. She could already see the bacteria taking its effect on him and was doing everything in her power to prevent him from seeing how scared she actually was.

Spencer had stopped working, Katharine having told him to rest a bit while she looked through everything once again. While looking for the cure and closing this case was near the top of her list, Spencer's wellbeing ranked higher than anything else.

Katharine wandered into the front room, by the sliding glass door and watched as they set up a biohazard containment tent right outside of the house. She waved at Dr. Kimura when the woman passed, telling her that they were doing alright considering the circumstances.

The doctor told her that it wouldn't be long before they could leave the house, that it wouldn't be long until they could get Spencer out and into a hospital. She thanked Dr. Kimura before making her way back to Spencer who had found himself a counter to lean against.

He had his phone in hand and he looked like he was having his own little mental debate.

"Uh," Spencer coughed, causing Katharine to rush over to his side. He leaned away from her as he coughed again, her hand rubbing soothing circles into his back. She bit the inside of her cheek as a deterrent to the worried look that she knew was beginning to make its way onto her face.

"I wanted to record something for my mom," Spencer explained after he finished coughing. He fiddled with the device in his hand, Garcia's contact information displayed prominently on the screen.

Katharine nodded in understanding. Even if she didn't want to think about it, these could very well be Spencer's last living moments.

"I can go if you want some privacy," she offered as she started to remove herself from the room once more but he surprised her.

Instead of letting her leave the room, he reached over and took one of her hands in his own. Spencer looked up at her and she could read the clear message he was trying to send with his eyes. He really didn't want to be alone right now.

Katharine returned to Spencer's side, clasping her left hand over his and squeezing slightly, letting him know that she was there for him.

He hit the call button and they waited for Garcia to pick up. Katharine brought Spencer's hand to her mouth and kissed his knuckles softly before letting their hands settle against her chest. She moved her thumb in circular motions on the back of his hand, reminiscent of what her mother did to comfort her when she was a kid.

"Hey, Reid." Garcia's tone was somber and sparkless. The usually bright and bubbly woman had no other words for their resident genius.

"Gee, wow, no, uh... No witty Garcia greeting for me?" Spencer asked. It was a weak attempt at a joke but Katharine appreciated that he was trying to keep the mood light. He coughed again, turning his head away from the phone.

"I can't be my sparkly self when you are where you are," the technical analyst admitted.

"Garcia, do you think you can do something for me?" Spencer's grip on her hand tightened briefly and Katharine squeezed back.

"Anything."

"I, uh... I know I can't call my mom without," he cleared his throat, "Without alerting everyone at her hospital."

"What do you need?"

"I, uh... I need you to record a message for her in case anything happens to me."

Katharine bit the inside of her cheek. If anything happened to Spencer... she couldn't think, or rather, didn't want to think about what that would mean for any of them. Despite the fact that she had only had four or five days of sincere interaction with the man, she honestly felt like she actually had known him for eight months and even longer through the stories Derek had shared with her.

Which meant she knew exactly how important Dr. Spencer Reid was to this team. He was like the glue that held them together, as long as he was around, the team would prevail.

"Oh, nothing's going to happen to you. You're gonna...brilliantly find out who did this and we're gonna treat this strain."

Spencer exhaled, his voice shaky, "I hope you're right, but if you're not, I just-- I really want to make sure that she hears my voice."

"Ok. just, uh, give me a second," there was the familiar clicking of keys on Garcia's end before she asked, "Are you ready?"

"Ready," Spencer cast his gaze downward and then back on the phone. "Hi, mom. This is Spencer. I just, um... I just... really want you to know that I love you and--" his words caught at the back of his throat. He had to clear his throat before he could continue, "I need you to know that I spend every day of my life proud to be your son."

There was silence. Katharine wrapped an arm around the man and he leaned into her touch, fighting back tears and making valiant attempts to steady his breathing.

"Reid?"

They heard the glass sliding door open. Katharine pulled Spencer in tighter for a one-armed hug before separating from the man. She cupped his face and wiped under his eyes, smiling up at him.

"You heard Garcia," she comforted. "You and your brilliant mind will figure it all out."

He gave her a weak smile, which was enough for her.

"Prep the victim for transfer."

Katharine let go of Spencer's face as the doctor rounded the corner.

Spencer uttered out a quick, "We gotta go," to Garcia after Katharine said her goodbye before hanging up the phone.

"Dr. Reid," Dr. Kimua addressed. "Agent Morgan."

Katharine turned her body so that she was facing the woman that had entered. The moment was over and they had to focus on getting Spencer out of this house and into a hospital. Hopefully, they still had enough time left.

"You look nice," Spencer commented on the doctor's bright red biohazard suit. It was a bold fashion statement but Katharine could see it being very apocalypse chic.

Dr. Kimura laughed. "I haven't been in this outfit for a while."

Spencer pushed away from the countertop but didn't leave Katharine's side. Their hands brushed together and Katharine linked their little fingers together in an attempt to calm the man down. It seemed to work because the taller man stopped fidgeting and instead asked about the patients that were at the hospital.

"Let's worry about you," Dr. Kimura said.

"I actually--I feel fine," Spencer insisted.

"Ok, if you feel any pain, I could give you something," the doctor offered.

"No, I--I'd rather not take any pain medication," he said. Katharine looked over at the genius, worry now painted across her features. It was one thing to remain inside the lab after being exposed but it was another to outright decline anything that might have helped him.

"We can at least make you feel more comfortable," Dr. Kimura tried.

"I am comfortable and I don't want to take any narcotics," Spencer's voice was firm and telling. Drugs were a sensitive subject, she figured. Katharine made a mental note to bring it up to him later on. It was either that or wait until he was ready.

"Ok," the doctor accepted. "Tell me how I can help."

"We think the cure for this strain is in here somewhere," Katharine finally spoke up. She detached herself from Spencer and headed back toward Dr. Nichols's workspace. Working would distract her from worrying about Spencer. He would be fine, there was help here now and he'd be on his way to a hospital soon.

"Well, shall I start here?" Dr. Kimura asked.

"Dr. Nichols is a former military scientist," Spencer told her. "Which means he's most likely secretive and most likely a little paranoid. He would have protected the cure and probably would have hidden it from his partners. So look for something innocuous, something you would not suspect."

"All right."

Spencer's phone rang and he coughed a bit before picking up. "Hello?"

Katharine looked over at the genius in worry, who just waved her off and told her to keep looking.

Katharine opened up drawers and started knocking on the back panels. It was something she hadn't thought about before, but she didn't believe the doctor would have just left the cure out in plain sight... or would he have?

Spencer was at Dr. Nichols's desk now, going through his binders and papers, reading off what the contents were. "I see a, uh, a framed photograph of Dr. Nichols teaching. I see a... I see a binder with syllabi. Course assignments going all the way back to the 1970s."

Derek must have said something to trigger his thought process because he muttered, "A teacher," before darting back off toward the other desk. "I saw something earlier. I didn't-- I didn't make a connection to it or to the partner, But he has a study on anthrax. He has an annotated bibliography, table of contents. It's formatted like a thesis and has writing in the margins in red ink, like the way a teacher grades a paper. Now, Nichols wouldn't have let just anyone in here, but he may have opened his lab for educational purposes, as a teacher."

Katharine tuned out Spencer's phone call. Derek would let her know anything she needed to know later on. She stood from where she was crouched next to the desk and surveyed the dead doctor's workspace a little more closely.

Spencer's frantic searching of the desktop had knocked a few items loose. There were some pens now messily strewn across the space. There was a glasses case and cleaner in the corner and Nichols's inhaler that had been dislodged from under a row of binders... 

Wait. Katharine grabbed the inhaler and examined it. There were no labels on it to show that it was prescribed to the doctor and it was still full, as far as Katharine could tell.

Katharine wheeled around as Spencer started coughing again. "Listen to this," he said into his phone. "'This country is woefully unprepared,' 'every household should have a two-month supply of Cipro. Hospitals are in need of biosafety level four Decon wings.'"

She furrowed her brows. "Spencer, that's verbatim to what we heard from Nichols. The partner has adopted Nichols' views as his own."

Spencer showed her the paper he was citing. "The chapters are on setting up triage and mobile emergency rooms. I don't think this paper was written by a science student. It's about city preparedness and response."

"So students in the social studies," Katharine deduced. "Public policy, urban planning."

Spencer had the phone on speaker now so that Katharine could hear the information that was coming in.

"Hot to trot," she heard Garcia's voice. "There's a Chad Brown, School of public policy at U of M. Matches a Chad Brown, a former employee at the book front."

"That's gotta be him," Derek said.

"Totally. He's been in the doctoral program on and off for five years. Nix on a steady job. Was slapped with a restraining order from his former girlfriend and has been arrested and released twice at protest rallies in DC. I'll tell Hotch."

"Kid, you did real good," Derek said. "Now get the hell out of there."

Spencer said goodbye and then he turned on Katharine, anxious to hear what she had found. Katharine pressed Nichols's inhaler into Spencer's hand, urging him to take a look.

"No prescription, it's a blank inhaler with a full canister," Katharine explained. "Spencer, you said the cure would be hidden somewhere we wouldn't suspect, right?"

Dr. Kimura reentered the room. "You found something?"

She looked from Katharine's hopeful look to the inhaler in Spencer's hand.

"Fingers crossed that we do, Doctor," Katharine said, showing her what they had found. "Fingers crossed."