Detective Jay Halstead and Detective Hailey Upton had been partners in Intelligence for over a year now. Despite both of them being in the force for many years combined, it wasn't lost on either of them that they were the best partner the other had ever had. Their first few weeks paired together had been a little rough, mostly in part due to Jay. He wasn't thrilled with getting assigned a female partner. Nothing to do with her gender, of course, but years prior he had dated one of his team members in Organized Crime. And while he thought their relationship had been great, she had been just using him as a stepping stone. The second Narcotics offered her a fat promotion, she walked away from Jay with barely a goodbye. He blamed himself for not seeing the signs, owning it up to being young, a few years removed from the war and just craving a taste of normalcy again. He was well over it now, and he certainly didn't want to judge Hailey based on someone she didn't even know, but still, he was definitely hesitant when their sergeant, Hank Voight paired them up. Add in the fact that Hailey Upton was also a natural looker who didn't even seem to realize it, Jay knew he should keep his distance. Somehow though, she broke down his walls, as he did hers, and soon they had become the best of friends. They both found that they spent more time with each other, between work and having to decompress from work, then they did with almost anyone else.

Which is why it wasn't a shock that Hailey knew Jay was too close to this case, despite him swearing to everyone else he was fine and could handle it. She knew when he was close to spiraling, she always did, she probably knew him better than anyone. The case at hand was trying to solve the arson of an apartment fire that caused the death of five people, including Jay's own father. His dad and him hadn't been close in years, in many ways they never really were. His dad always took to his brother, Will, more. Will was a doctor, spending years studying and applying himself to get out of the Blue-Collar lifestyle that Pat Halstead had worked so hard at so his sons wouldn't have to. So he hated the fact that Jay wasn't studious, hated the fact that Jay had decided to join the army for pennies and risk his life, and then really hated the fact that when his son survived all of that, he chose to become a cop. Add onto the fact that he was a mad-at-the-world Irish drunk who could barely take care of his mother when she was dying from Cancer, Jay hadn't been a fan of his father in a long time. But at the end of the day, your parents were still your parents, we love them in our own ways, and Jay wasn't handling his death anywhere near as well as he thought. Hailey had kept her eyes close on him all week and they had butted heads plenty. She had never been scared to call him out on his shit. She cared, and she was worried.

They had finally found a break in the case. One of the deaths had been Edgar Torres, the leader of the Sinaloa Cartel, so the whole fire and innocent death lost from it had been all over a drug hit. If Jay had been angry before, he was livid now. He stormed off to the lockers the second the team found out, with Hailey hot on his heels. She found him banging his fist into one and then leaning his head on it in defeat. She approached him tentatively, softly laying a hand on his shoulder and squeezing, letting him feel her presence.

"Hey." She said sympathetically. "Jay, look at me."

He finally looks up again to face her with sad, blanks eyes.

"I really think you need to sit this one out now…" she whispered gingerly, hoping to finally get through to him.

"Hailey, for the hundredth time, I AM FINE! My father did not just save someone's life and lose his own for me to sit back and let some gang wannabe get away with murder."

"Jay-"

"I SAID I'M FINE!" he tells her angerly and pulls her hand from his shoulder.

She stares at him, her patience wearing thin, but the hurt showing on her face that she can't hide from him. He instantly feels remorse, knowing she's just trying to help.

"I'll be okay, really. Look, let's just get the bastard who did this, and then I'll take the time to process everything, I promise." He tells her in a much calmer voice.

She swallows the sigh she has and just nods at him, hoping she won't regret the decision to let him continue on with this case. He squeezes her shoulder this time and they make their way back out to the bullpen.

As the case went on the team discovered that it was Edgar's driver's son, Daniel, a low-level player in the cartel who wanted to make a power move to rise up the ranks; so he killed Edgar and started the fire to cover it up. It was Jay who came up with the idea to bring on a fake charge on Daniel's brother Juan, "the good son" to get the father to flip on Daniel. Not everyone was on board with this, considering it was an innocent man's life at stake, and tensions started to rise even more.

Hailey quickly interjects. "Okay, it's too risky. We get Juan involved, then he's actually involved, the cartel starts gunning for him too!"

"Yeah man, that ain't right! There's gotta be a better way to do this." Adam Ruzek, another team member, agrees.

"Like what?" Jay asks as the team all shares looks. "Exactly, we're at a dead end. I don't even know why we're debating this."

Hailey looks on aghast. She can't believe Jay, who normally shares the same moral compass as her, is even suggesting something like this. She recognizes that this is still affecting him more than he's willing to admit, but she can't agree with what he wants to do.

"Because we're playing with an innocent man's life, Jay!"

"Five other innocent people died because of this guy's not-so-innocent brother and father. So I'm sorry if my heart doesn't bleed like yours!" he responds to her angrily, his frustration boiling over.

Hailey sits up straight now, completely shocked by his direct attack. "Excuse me!?"

As she's about to say more, Voight butts in to break it up. "Okay. That's enough. It's what we have, it's what we'll use. Bring him in."

Jay gives Hailey a pleading look, hoping she'll understand it. He knows he overstepped, but it's not like he can just come out and apologize in front of everyone. He hates that he keeps coming at her especially, but his walls aren't holding up as well as he'd like, and she's the one he's closest to. She's too pissed off herself at this point, so she just looks back at him in disgust and makes her way to the cars.

While Jay, Hailey, and Adam are waiting outside to grab up Juan, Hailey looks at Jay cautiously, fearing how he'll handle this situation. Things escalate once Juan comes out and refuses to go with them willingly. She knows Jay is ready to blow, but trusts him to let it play out. Wrong move. After talking with him didn't go the way Jay wanted it to, he quickly grabs Juan and puts him in a choke hold. While Adam tries to break Juan free of Jay's grasp, it's Hailey who finally halts Jay and pushes him off.

"Jay, back off. BACK OFF!" she screams as she finally breaks through to him. Once Adam has Juan in custody and safely away from Jay, she shoves him again for good measure. She's really angry that she trusted him to stay calm. "You good?" she stares up at him, her eyes fierce.

"Yeah, I'm good." He finally says raising his hands to show defeat. He's terribly irritated with himself now because he knows he keeps setting Hailey off too, but he just doesn't know how to stop himself.

A few hours later they get Daniel's father to call his phone so they can ping his location on the clause that they'll release Juan. Jay heads over to meet Voight with Hailey before the takedown. He has a million ways he wants to apologize in his head, but nothing will come out.

"Hailey…" he starts while quickly looking over at her from the driver's seat.

"Don't Jay, not now. Let's just get through this." She says back to him coolly.

He nods his head at her and before he knows it the car ride is over and they're hopping out to talk with Voight, Jay having no idea this was a setup to keep him away from the remainder of the takedown.

Voight talks over the walkies, "Alright, as soon as we get the location, teams move out. You get there first, you hit it…" once he confirms the rest of his team is good, he turns back to Jay. "Jay… you're not coming!"

Jay turns to look at Hailey first, feeling betrayed. "What?" he asked them both shocked.

"Give her your keys and your two-way." Voight responds in his no-bullshit way.

"You gotta be kidding me." Jay says while replying to Voight, but only looking at Hailey, in complete disbelief.

She looks sad for him, but knows this is in his best interest.

"It's for the best, Jay. Keys and the two-way." Voight reiterates to Hailey again as he starts to walk back to his car.

Hailey finally responds to the situation, trying to be as soft with him as she can. "You're too close to this Jay."

"What the hell does that mean?"

She continues to looks at him sympathetically. "He's your dad…"

"What did you say to him!?" Jay asks her signaling to Voight.

"I didn't say anything!" she replies defensively as they talk over each other.

"You don't know anything about my dad." He responds in anger again.

"I'm not pretending to!" she yells back, her frustrations starting to boil over now as well.

"No, you're just projecting whatever daddy-daughter crap got you screwed up!"

She ignores the low blow and just continues on. "Okay, I'm done being your punching bag. Give me your keys."

He stares down at her and she stares back defiantly.

"GIVE ME YOUR DAMN KEYS!" she yells again, completely over this whole thing at this point.

He shakes his head realizing she's not going to budge from this and hands her his keys.

"Two-way." she responds quickly, not leaving any room for a debate anymore.

He hands it over to her and she swiftly walks to his truck to drive away with Voight, not even bothering to glance in Jay's direction again. He's run her through the ringer these past few days and frankly she's over it. Jay sighs as he watches them drive off, hands on his hips. He knows he's overstepped, especially with Hailey, but he has to see this through. He owes his dad that much. He makes another foolish move and calls Kelly Severide, a local firefighter and friend who offered to help, to pick him up and gain access to his two-way.

Within minutes later Jay has spotted Daniel before his team could and is chasing him on foot down the streets of Chicago. The two come to a standoff while under an overpass, both shooting at and striking the other, falling down to the ground. Jay hears Daniel gurgling out for help as he feels the blood on his side. He can't tell how severe his wound is, but is worried his vest didn't protect him. He knows Daniel is worse for the wear, so he crawls his way over to him, radioing for help. He feels for Daniel's pulse before collapsing on the cold, hard cement. The pain is immense and he knows he's bleeding pretty badly. If this is how it ends, he realizes that his one regret was going to be arguing with Hailey as his last moment with her. She tried to be there for him all week and he continually pushed her away. Leave it to him to screw up one of the few good things that's come into his life the past couple of years.

He starts to hyperventilate, but swears he hears her voice come through his fog. "5021 Henry, officer down, I repeat, officer down, Lower Wacker and Columbus, Get us an ambulance… Jay!"

He feels her soft and warm hands on his chest now as he hears the fear and panic in her voice and Adam yelling in the background.

"Jay, you okay? Come on." She calls out as she tears open his shirt, quickly checking his vest once she does. "It didn't go through; it didn't go through. It's okay." She quickly says as she tries to maintain the shakiness of her voice and hands. "Jay, Jay, breath, breath. You're okay. Okay." He hears her trying to keep him and herself calm.

She puts her hand to his cheek and he leans in slightly, trying to hold back his tears. "Okay." She repeats again, and he's not certain if she's trying to assure herself or him more. She doesn't leave his side until the ambulance arrives, Voight calling her over to finally give her statement to the other officers. She keeps glancing his way though, through Jay's entire checkup and Voight reaming him out, Jay can feel Hailey's eyes on him. Once he's alone again, he sadly watches her walk back over to him. He owes her so much after this week.

He doesn't know how to start, so he just simply asks her about the job. "Daniel?"

She looks at him sorrowfully. "He was pronounced at Med. Antonio's with Juan and Carlos, he's taking them into protective custody. DEA says bodies are already dropping in Mexico, so…"

"So a happy ending?" he asks her and she just smirks at him as they sit quietly for another few seconds.

"Hailey, um… I just couldn't stop myself…"

She nods in understanding, blaming herself for this as much as she blames him, and gently places her hand on his knee to offer comfort. She should have gone to Voight and told him to pull Jay right from the start, but she knew her partner had to see this through. He was as stubborn as she was. Look where it got them though… he could have died. When she thinks back to her and Adam rounding that corner and seeing Jay lying there motionless in a gutter, she tries to choke back tears. Jay notices instantly and places his hand atop hers.

"Hailey, hey, look at me. You okay? I'm so sorry for putting you through this."

She takes a deep breath and wipes away some tears with her other hand. "I thought you were dead…"

Jay looks at her sadly and his heart starts to break knowing he did this to her. It's not often she lets vulnerability show, so he knows she must really be hurting by this. He removes his hand from atop hers, and weary of his injured ribs he slowly puts his arm around her and pulls her into him.

"I'm okay. I'm alright. Won't even need to be put on Light Duty." He whispers in her ear trying to reassure her. "You know how much I would hate that."

She laughs lightly. "Yeah, you would be insufferable!" she jokes back.

They pull away and chuckle together, staring intently, and getting lost in the moment. The tension surrounding them becomes palpable, and they're both drawn to each other in a way they never have before. She watches as Jay's eyes drop to her lips, looking at her in a way that went well past the boundaries of partnership.

"Jay—"

Before she can continue, they're interrupted from their magnetic pull when they hear some commotion coming over by patrol. A woman's voice sounding frantic, finally breaking through the police barrier. It doesn't go unnoticed by Hailey the small groan Jay lets out as his girlfriend, Claire, comes running over to them. The two instantly separating themselves further apart.

"Oh my God honey, Will just called me on my way home from work. I rushed over here. Are you alright? I was so scared!" she says as she touches his face and inspects the rest of his body.

Jay places his hand on hers resting on his cheek. "I'm fine. Just some injured ribs and a potential scar. Plus, a reckless ego that Hailey probably should have killed me herself for, but that's nothing new." He tries to joke to both women.

"Hailey, thank you for saving him. I still can't believe your boss let him work this case. Well, honestly I can't believe how you guys do this job, but I'm just glad you're all okay." She says giving Hailey a hug, surprising the detective.

"Saving his ass is literally what I get paid to do, so it's no worry." She says, trying to make light of the scenario in front of Claire, knowing it's what Jay would want.

She hops down from the ambulance bay and lets Claire take her spot. Jay and her sharing one last look while Claire continues to fawn over him. Jay knows she's about to leave and he wishes he could do anything to get her to stay.

"Hey, you know, Will, Claire, and I were gonna grab some takeout after we look through some of my dad's things. You should join."

Claire nods in agreement, but Hailey would like to be anywhere but around them after the weird moment with her partner just minutes before.

"Thanks, but I'll have to raincheck. Nathan's been texting me all day about when I'd be off and I've barely seen him all week with everything going on, so I should get home. Definitely over the weekend though if you guys need more help. Rest up, partner. Claire, good to see you despite the circumstances."

Hailey replies and quickly starts to turn around before either can respond. She inhales deeply as she feels Jay's eyes burning a hole through her head as she walks away. This far into their partnership she can sense them anywhere… what she doesn't know is how depressingly glum they look as they follow her until she's a small, dark blurb in the distance he can hardly see anymore, but the one thing he wants to hold onto...

[A/N: Join me for a journey of another slightly AU Jay and Hailey story. The majority will take place in the time of season 6 of the show, with some flashbacks to 5 and potential future season jumps. Hope you enjoyed this start and thanks so much for reading!]