It was a cold day in Chicago. Actually, make that a cold week. And it was affecting everyone's moods. Nobody liked dealing with -20 temperatures and moods seemed to suffer even worse the more the mercury dropped.

And both Jay Halstead and Hailey Upton's moods were downright awful. They were arguing, fighting over the most inconsequential things and even Antonio had to come into the middle to settle a disagreement between them. Voight just chuckled and knew they'd work it out when the weather warmed up. But in the meantime, it was awful to listen to for everyone else in Intelligence.

Hailey's moods got worse the more awful she looked, Jay noticed. He knew how horrible his partner looked. She looked like shit and that was part of the arguments, he tried to tell her to go home and rest and she didn't like that. They were in a restaurant, waiting for Chester, one of Hailey's long time confidential informants to arrive.

Chester was an interesting character and Jay had met him before, even on his own. He was a preppy rich kid and on his way to making his own money, the shady way, and apparently one of her best CI's. Jay knew there was more to the story so he didn't judge too badly. And Chester came in beaming like he had just completed a big money deal when he walked in. "If it isn't the happy couple," he greeted them.

Both Jay and Hailey rolled their eyes. "You gotta stop greeting us like that," Jay said.

Chester shrugged. "Throws you off your game."

They caught up a bit, Chester gave them the information they needed and Hailey went to go pay for their lunch. That's when Chester leaned in across the table. "Dude, man, you gotta get her looked at."

"What do you mean?" Jay asked, glancing at Hailey, who was grabbing the waitress' attention. At this restaurant, if you didn't go up to the front to pay, she wasn't coming around and you weren't leaving anytime soon.

Chester looked at Hailey and back at Jay. "She looks like fucking shit, man. I haven't seen her look that bad since I dragged her to the hospital 3 years ago when she was undercover and she spent 5 days in ICU. I spent it hoping she wouldn't die and nobody from CPD bothered to check in."

Jay filed that in the back of his brain to use for later. "Yeah, I know. I've been telling her that she looks sick but she insists she's fine."

"I've known Hailey for five years, Jay," Chester said. That was probably the only time he had ever called him Jay. It was always 'hey man,' 'hey bud,' or something along those lines. "Get her to the doctor."

"I got some connections. I'll do it," Jay promised as Hailey made her way back to the table.

Jay and Hailey made their way back to the truck. Chester was right; she needed to see a doctor before she ended up in the hospital. Jay just didn't know how he wasn't going to get her to see one. She had the keys to the truck but she just threw them to him for him to drive.

She was silent for the first five minutes and then finally spoke. "Can you just drop me off at home? I feel like shit. We're close to my place anyways." There! She finally admitted it.

"You're finally admitting it?" Jay asked. He signalled to turn so he could drop her off. "Yeah, sure."

She scratched her cheek. "Yeah, this headache won't go away."

They were silent again until he pulled up in front of her house. "I'll just pick you up tomorrow," Jay said. "Normal time?"

Hailey hesitated. If they picked each other up to workout, it was usually 7. "Make it 8." That was a clear indication there was no gym involved.

"Hailey, if you need anything tonight, fucking call me," Jay said before he heard the truck door slam. He just rolled his eyes and made sure she was inside before he drove away. He'd text her later.

He got some curious glances when he got back with no partner. It was later in the afternoon, 3 pm, but Hailey didn't just skip out on work because she didn't feel like working. "Dropped her off at home. Finally admitted she felt like shit."

Voight shrugged. "Can't force her to go to a doctor, Jay," he reminded him.

"Yeah, except I'd like to know that my partner has my back. Her CI said something though," he said.

Voight nodded towards his office and Jay followed him in and closed the door behind him. "Yeah. Chester Park? Interesting guy."

"Interesting is a way to put it. Said he's known Upton for awhile and said, I needed to get her to a dr before she ended up in the hospital like the last time. Referenced to an undercover op where he dragged her to the hospital and she spent 5 days in ICU?"

Voight grabbed a file and handed it to Jay. "10th page, third paragraph. Figured it might come up and her hesitation to go to the doctor or hospital."

"Well, when you wake up with no one there except your crew leader's bodyguard and not a clue how you got there after 5 days, I'd have a problem too," Jay muttered.

The Sergeant nodded. "Yeah. That little incident made it all the way up to the Superintendent, Upton's handler got fired on that IA investigation and Chester made some heads roll, silently, of course."

"He is a good CI."

"The best ones are always the most painful to deal with. Keep a close eye on her."

Upton knew she was being unreasonable to deal with but holy shit, she felt horrible. Like utterly horrible. When Jay texted her that he was outside, all she did was open the back and put her bag in the back seat, get in the passenger seat and nod her thanks when he passed her a Starbucks. Her head was pounding, she already had multiple cups of coffee but nothing was working; she appreciated the gesture though. Being a cop, she couldn't take anything more than an aspirin being on duty.

She had made it through about three lines of paperwork before she needed to go puke. She found herself in the locker room throwing up her attempted go at breakfast, coffee and everything in between. And it wasn't stopping. And then somebody came into the locker room and the door wasn't closed to the only bathroom.

Platt saw her leaned up against the wall and immediately rushed in and held Upton's hair as she heaved into the toilet again. "How long have you been like this?"

"Only ten minutes," Upton muttered as she flushed the toilet again.

She could barely sit up and Platt basically had to hold her and she felt her. "Hailey! You're burning up!"

"Yeah, and I have the worst migraine from fucking earth. It's been here for four fucking days," Upton said, before she had to throw up again.

Platt shook her head. "That's it." She stepped outside and yelled at Burgess to come inside and be with Hailey. "I'm going to get you something to puke in on the way to Med, but Halstead is taking you to the hospital."

Upton shook her head and Kim and Trudy both looked at each other. "Hospital," they both said in unison.

Platt went to go grab Jay. "You need to take your partner to the hospital."

He looked up from the computer. "Uh, what?"

"She's in the bathroom, puking her guts out and has been for the past ten minutes. I'm pretty sure she has the flu as well as a migraine, so she's going to the hospital. I'll get her something to puke in on the way."

Halstead nodded at her as he got up and grabbed his jacket. "Thanks Trudy."

Burgess looked up at him sympathetically as he entered the bathroom. Hailey was slumped up against the wall with a horrible look of pain on her face. She looked like she was in agony. "Come on. I'm taking you; you don't have a choice. You're other choice is Platt and I'm way better company than her," Jay tried to make a joke.

Platt came back to hear that and handed him a bag. "I heard that, but he's right."

She slowly started to get up and winced several times before making her way to the door. Burgess grabbed Upton's jacket for her and handed it to her as it was still bitterly cold out and they made their way to where Jay's truck was parked. Hailey was a little secretly glad she was going to the hospital as she didn't stop throwing up the entire way there.

Jay parked close and walked in with her and made it abundantly clear he was not leaving her side all day. Maggie was the first to greet them. "Platt called. Room three. Your brother will be in there in a second."

Maggie guided them to the room and got Hailey sitting up in the bed before she started puking again. "Oh honey," she said, sympathetically.

Will entered the room as well and arched an eyebrow at his brother. "This one's yours?"

That made Jay crack a smile because Hailey would hate to be referred to as anyone's. "She's mine. Detective Hailey Upton, meet my brother Dr. Will Halstead."

"Nice to finally meet you," Hailey said. "Wish it was under a little better circumstances."

Will sat down and started taking notes. "What's going on Detective?"

She looked at Jay, who was leaning against the wall with his arms crossed, and knew she wasn't getting out of this with the whole truth. "I feel like shit. I have for five days now. I've had this god awful migraine and I can't get rid of it. Nothing works."

"Have you had migraines before?"

Hailey nodded. "Back in University I had them really bad. I'd have a solid one for three weeks straight, bad. I have had one in 5 years though."

"Have you taken anything for it?"

"Excedrin?"

"That's it. For someone who's been around the block with migraines, I'd expect you would know what to take."

She shrugged. "Back then, I didn't have a job where I couldn't take anything stronger than an aspirin on fear of an IA investigation if I had to have one."

He seemed to take that as a reasonable answer. "Any other symptoms?"

"Fever, chills, basically feels like the flu combined with the worst migraine ever," Hailey replied.

Will looked at her belt and the Detective shield on it. "And you went to work today?"

She shrugged, he looked at Jay and finally Jay spoke, even though what he said might put him in the doghouse. "She's been miserable to deal with the past few days."

Hailey didn't counter that. "Just get rid of this migraine please."

"We will swab and see what flu virus we are dealing with but minimum two bags of IV fluids today so you two will have lots of time to get to know each other's worst kept secrets," Will laughed. He looked at Hailey's veins. "You're dehydrated, so it's going to be fun to try and stick an IV in here but Maggie is a pro at them."

"Thanks," Hailey said, softly.

Jay also nodded his head in thanks.

"Anything for Chicago's finest. I'll be back in half an hour and see if the drugs have started working."

Jay turned to Hailey. "You're stuck with me, sucker."

Jay had no idea what drugs would do to Hailey but they made her very happy. Like incredibly happy. So much so that he had no idea what to do with an over the top happy Hailey. They had been in the hospital for most of the day, as Will and Dr. Choi had wanted Hailey to get as much fluids as possible in her body, especially with her having the flu on top of her migraine.

"Can you stop at Francine's and get me a ridiculously large tropical tornado smoothie?" She had said it with such a smile on her face that he couldn't help but go out of his way to Francine's drive thru and get her favourite smoothie.

The next stop was the liquor store and although he would be keeping alcohol a fair distance from her tonight, he still wanted beer. "Why can't we have wine tonight, babe?"

Jay tried so hard not to burst out laughing. Hailey had blown through the first doses in the hospital and Dr. Choi, after Will was off shift, had to give her more and those second doses were not wearing off. Which was good. The pain needed to stay gone. "Babe, I don't think you need wine tonight. Plus, you don't even like wine," he said playing along with it. He didn't want to set her off right now. Better to play along.

She just shrugged as he paid for the beer and walked out. Their last stop was getting pizza. This time it truly was Hailey's turn for her favourite pizza and she insisted on coming inside when he picked it up, which he didn't mind because it wasn't quite ready yet. Her arm was around his waist while they were waiting. He just found his partner quite amusing tonight but he was willing to roll with it.

"Whatcha thinking about?" she asked him.

He looked down at her. "Whether I'm going to remind you or tell you tomorrow what you are like really like on Dilaudid and whatever concoction my brother put you on."

AN: last part is inspired when a good friend took me to the ER last week for a migraine and I was straight up out of it after (I normally can handle my painkillers) and apparently I was hilarious. Who knew! So out came the plot bunnies late tonight and this came out on paper. Enjoy!