Title: A New Understanding

Summary: After a tough shift and a tense argument, Casey and Severide part ways in heated disagreement. But in the parking lot one is jumped by two angry men wanting some payback, forcing the other to take action and a new unspoken understanding to form.

Disclaimer: Chicago Fire and its characters are the property of Dick Wolfe, NBC and….well sadly not me lol

A/N: Thank you everyone so much for all your amazing reviews for my last CF OS, it gave us confidence to try out hand at another. And we thought that while we waited to see what move Voight makes next so we can come back to our warning series, my muse Alice and I would try our hand at another one shot and hope you all like it as much as the first.

To most of the guys at Fire House 51, dealing with tension-filled situations was something they had gotten used to and had taken the job for. Witnessing their two Lieutenant's arguing over a call in the field was also something they had gotten used to; most of them knowing when to interject and when to back off. Tonight was the time to just back off and let them both blow off steam and hope the weekend ahead would just serve to foster better feelings coming Monday.

"That kid is alive because of what I did."

"Your so called heroics put two of my guys in danger!"

"It was your job to pull your guys back when I told you to. Had you done that they wouldn't have been in danger…only me. You're pissed because my high risk called saved that kid and made your…"

"Your call put my men's lives in danger. You didn't wait for me to get there…"

"I wasn't the one…"

"There a problem here gentlemen?" Chief Boden's stern voice finally interrupts, looking at them as a principal would two well known but stubborn children.

"No," both grown men mutter at once, Severide just shaking his head as he turns to leave; Casey remaining behind but shaking his head and muttering as well.

"Chief…" Casey starts.

"The call was made and in the end the call was ultimately mine. That's it, it's done," the Battalion Chief insists. "Go home and sleep it off. Enjoy the day tomorrow. No one died today…it was a good day."

"Goodnight Chief," Casey mutters as he watches his boss take his leave; a few minutes later, pulling away from the cold metal of the locker door and opening his own, grabbing his jacket and wanting nothing more than to get home, have a cold beer and just restart the day.

'Severide no! That ledge isn't stable. Herman could go…'

'Tell him to get off…it'll hold me! I'm closer! I can reach the boy…'

"Always have to be the hero," Casey mumbles with an exasperated sigh as he slams his locker shut and heads for the back door, wanting to just slip away and be thankful as the Chief said, no one died today. 'That man…he's a hero…he saved my boy…' Casey hears the father's voice in his head as he pauses at the door to go out. He hears Severide's voice behind one of the trucks laughing about something and can't help but smirk at the lame joke before he ducks out into the night; his frown returning.

Casey heads for his truck, his fingers jingling the keys and his mind not really paying too much attention to the two dark figures sneaking up on his left; his mind still distracted by the near miss a few hours earlier. Sure the call worked and he would be lying if he said he wouldn't have done the same thing if the situation was dire. But…

But we're a team and the team was there…damn his…his mind trails off as he hears another jingle behind him. Figuring it was his fellow 51 Lieutenant, Casey doesn't turn around. "Hope you and that ego sleep well," he mutters under his breath. But not hearing even a snide comeback in return to rebut his offhanded remark, Casey turns to see just who the odd jingling is coming from. However, just as he turns the right side of his cheek connects oddly with the end of a hard fist, snapping his head to the side and forcing his own keys to fall to the ground.

"Wha…" is all he manages before his arms are pulled behind his back and the second dark figure steps in and lands a hard blow to his stomach, forcing his body to double forward before he's painfully forced back upright.

"Remember me?" A male voice sneers as he leans in closer, his face now illuminated by the overhead parking light.

With a slight wince from the pain now reverberating through his tired frame, Matt Casey's mind races to put together a name with the angry face now staring him down.

"Do you?" The man demands harshly before another blow is delivered; the second man keeping Casey's arms firmly trapped behind him and his chest exposed and vulnerable.

"No," Casey wheezes as the man curses angrily. "Who…are you?"

"You let my brother burn!" The man shouts with a hiss.

"What?"

"He died because of you!"

"Who…is your…brother?" Casey manages with a soft gasp as he doubles forward again and is pulled back upright; his lungs nearly winded from the last blow.

"Duncan Rhimes and you let him burn! You told your men to clear out. You left him to burn! I watched!"

"Rhimes…he was dead…my men…"

"Shoulda went back in! He was still alive!" Vincent Rhimes shouts as he delivers a blow to Casey's mouth, busting open a small portion of his lower lip and forcing his throat to gag on the coppery taste of his own blood now swirling around on his tongue.

"Wai..."

"Over there…in the shadows. This is justice where I come from."

"Wait, you've go…" is all Casey manages as his body struggles to get free of the two sets of arms dragging his very unwilling frame toward the waiting shadows; this tongue trying in vain to push out the cloth now stuffed into his mouth to keep him quiet; desperate to draw any attention to his dire predicament.

"Now it's payback time."

XXXXXXXX

"See you Monday," Kelly Severide calls out as he waves goodnight to the last of his guys as the part ways, Severide heading for the back parking lot he had seen Casey heading for earlier. "It was my call and a good call…" he tries to justify to himself, his mind reminding him that it could have gone the other way and ended with a much worse outcome than what miraculously happened.

He pushes through the back door and pauses, looking at Casey's truck with a frown but then figuring maybe his Lieutenant counterpart slipped back inside through the front to finish something up. He nears Casey's truck and stops, squinting as his eyes pick up a small glint of silver being caught by the overhead light.

"What the…can't get to far without these…" his voice dies out as he picks up Casey's keys, looking at the locked truck and then looking around. "Casey? Hey Matt you out here?" Severide's voice calls out in question; his mind wondering what could have happened. With the keys still clutched in his fist, Severide turns and heads back inside, walking up to Robbie the janitor with a perplexed expression.

"Evening, Lieutenant Severide."

"Hey Robbie, you see Matt Casey come back in here?"

"No. I saw a light on in the locker room. Maybe he's still in there? But I haven't seen him since he left about fifteen minutes ago."

"Right…thanks," Severide mumbles as he heads for the locker room, wondering what would have made Casey so careless to drop his keys. Bad call or not, he's not careless, his mind surmises correctly as he enters the quiet room and stops. He heads for Casey's locker and pulls it open; jacket gone but everything else as it should be. "Your nickname should be Mr. Clean," he mutters with a hint of sarcasm and a light smirk as he turns and heads back toward the truck area; scanning the quiet space and wondering what was going on.

"Casey!" Severide calls once more as he enters the parking lot for a second time in ten minutes; his anxiety starting to swell at Casey's unusual and silent absence. Having it mostly as an emergency contact, Severide pulls his phone and dials Casey's number; turning sharply to the right and squinting into the darkness where the faint but distinct sound of the phone ringing is directing him.

"What the…" he utters as he hurries toward the darkened area, rounding the back of a van and stopping short at seeing two guys standing over a third on lying motionless on the ground; about to be kicked in the stomach. "Hey! What's going on here?" He demands as he rushes toward them, the two men cursing as he nears; turning toward him and charging.

Three bodies collide, stumbling close to the ground in a jumble of arms and legs. But since Severide wasn't the one they came for, the two angry men give him a good shove toward the darkened shadows and race for their car on the other side of the van, peeling out of the parking lot in seconds.

"What's…going on," Severide grumbles as he rolls onto his stomach and then looks a few feet to see a cap of dirty blond hair, the rest of the familiar frame hidden in the darkness. Without wasting another second, Severide pushes himself up and hurries to Casey's side, instantly checking for a pulse. "Oh damn."

"Hey can you hear me?" He asks softly as he gently pulls the damp and blood stained cloth from Casey's mouth and gently taps his cheek. "Hey…Matt…come on buddy…hey man open your eyes."

Not getting any kind of verbal response he gently feels Matt's chest, hoping for any of response if there were indeed hidden injuries from the very one sided fight.

"Okay I'm not feeling any broken ribs but I gotta get you inside," Severide talks to himself, wondering now the best way to get Casey inside without hurting his neck or straining his arm. "You better stay out for this carry," he grumbles as he moves himself into position and prepares to hoist Casey into the air and get him back into the warmth of the Fire House.

XXXXXXXX

You let my brother burn…he died because of you…he was alive…he burned to death! You killed him!

"Ahhhh…" Casey's lips utter a small gasp as his brain tries to force him back to reality. His mind replays the surprise attack, his feeble and short lived attempt at trying to explain the truth and then feeling blows rain down upon him before he started to lose consciousness, his mind thinking he heard Severide's voice calling out to him but telling himself that would never happen.

His somewhat watery blue-gray eyes slowly flutter open, rapidly blinking and trying to get the room to come back into focus, his brain yelling at the ringing in his ears to subside.

"Welcome back sleeping beauty," he hears a soft but familiar voice as he turns his head and squints at the person to his right.

"Severide…what the….hell happened?" He slowly stammers as he slumps back down onto the cot that he had been placed; the small room in the back that was used for mostly emergencies.

"You tell me."

"I…" he winces heavily as he tries to sit up, Severide's hands gently pushing him back down.

"Just rest okay. You just lost to Tyson in the first round."

"Feel like it," he huffs as he slumps back down, his fingers gingerly touching his face. "How do I look?"

"Like you just lost to Tyson in the first round," Severide repeats with a soft frown as he hands Casey a cool damp cloth.

"Thanks," he offers weakly as he dabs his wet lip and then looks at the small amount of fresh blood with a frown. "It was Rhimes brother."

"Rhimes?"

"School fire. His brother was the janitor. Said I let his brother burn…to death," he lightly gasps as he tries once again in vain to sit up.

"And you call me stubborn, just rest okay."

"You are," Casey retorts.

"His brother was already dead."

"Tried to tell him that…" his groans as his fingers start to feel his chest.

"Already checked you…nothing broken," Severide informs him in truth.

"Okay," he subsides once more, his mind racing to indentify other pain centers in his body from the painful altercation. His chest was mostly on fire, but thankfully Severide's timing kept him from spending a night in the ER; something Hallie would have frowned at for sure. "I gotta talk to him."

"Talk to him? The guy that just…" Severide states in haste as he watches Casey try to sit up once more, this time not stopping him.

"I gotta explain…ahhhhh," he wheezes as he looks at Severide with a strained expression.

"You taking the cops with you? Because you can charge him with assault."

"I know."

"But you won't," Severide shakes his head.

"He has to…ahhhh damn," Casey curses again as he tries once more and slumps back down.

"What? You want me to tie you down to that thing?" He counters with a mock smirk.

"I'll go…in a bit," Casey slumps back down to a horizontal position, wanting to wait for the throbbing pain in his chest and lungs to subside so he could state his case without falling down. "He needs to know."

"He could have gone to the hospital, they would have told family."

"He blames me. It has to come from me," Casey insists.

"He's angry and might not care."

"He still needs to know the truth," Casey manages as he purses his lips but instead of saying something more, offers a heavy sigh and another painful groan as he tries to twist over onto his side. "Glad you came along…when you did."

"Yeah can you imagine your guys under my command?" Severide tosses out lightly, forcing Casey to look over with a frown and Severide to smirk.

"Nightmare."

"For us both."

"That kid…"

"You just got the crap kicked out of you and you are still on about the call?" Severide asks in mild surprise. "Doesn't your lip hurt to keep talking?" He adds with some sarcasm.

"Was my call."

"Yeah so was Rhimes."

"So what you're saying is…" Casey starts as he lifts himself upright to a semi-seated position to argue further. But taking a deep breath, his chest offers a sharp bout of pain and he quickly slumps back down. "You sure nothing's broken?"

"Lift your shirt and I'll see if there's new bru…what? Trust me it won't turn me on," he winks, making Casey roll his eyes but gingerly lift his shirt.

"This hurt?" Severide asks as he carefully starts to trace the outline of Casey's ribcage.

"Yup."

"This?"

"Yup," Casey winces.

"This?...okay it hurts but doesn't feel broken. Just some heavy bruising. Maybe a crack or a fracture. Head on down to the ER and get some x-rays if you wanna be sure."

"No it's good," Casey replies as he slowly lowers his shirt, thankful again for the added warmth from the somewhat dirty fabric that had collected dirt from the ground when he had fallen earlier. "Just curious…how did you know where I was?"

"Found your keys and figured you wouldn't just leave them there…checked back inside…and then called your number and followed the ringing."

"Thought I heard that but then thought it was just in my head."

"Probably was that also. They saw me…took off and…and here we are. And tonight was supposed to be a fun night out after work."

"It still can be. You can go home now…thanks for the help."

"I will if you do."

"I will…"

"After you talk to Rhimes brother?"

"He needs to know. Then I'll go home and pass out…promise," Casey states with a soft whisper as he tries to get off the cot and prove to his colleague that he is more than capable of walking out on his own and carrying out his intended task. But standing up too fast only serves to send blood to his head in seconds, causing dark circles to form and the room to instantly spin.

"Hey I got you…" Severide quickly jumps up before Casey's already weakened frame can crumple to the floor and possibly do more damage than had already been done. "And you call me stubborn; just rest here a bit longer."

Casey grumbles a small thank you as he allows himself to be helped back to a lying down position, cursing the fact that his head is now pounding more than before, the sudden urge to stand upright impeding his healing process. He utters a heavy sigh into the quiet room as he looks over at Severide and frowns. "I'll rest here an hour and then go. Deal?"

"You're making a deal…on feeling better?" Severide tosses back, as Casey's eyes briefly close. "You're worried I'll think you weak?"

"It doesn't matter," Casey retorts.

"Obviously it does. Well you can't drive there and you know it; not if you can barely stand. What if you cause an accident? Lead by example right?"

"Okay you can quit the damn lecture…that's my department," Casey huffs, making Severide lightly chuckle. "What? I know what you say about me."

"Would it kill you to just loosen up a little?"

"I'm loose now."

"Great so every time you want to loosen up you just need someone to kick your ass? You really wanna put that out there for me?" Severide lightly jokes.

Casey doesn't answer, merely dabs his mouth and then lightly curses as the cloth still comes away with fresh blood; his nose thankfully, no longer bleeding. A few seconds later, Severide's phone rings, prompting him to leave the room and Casey to strain to hear what the conversation is about.

"No I can't make it tonight…I gotta help…someone. No it's not another woman…a friend…from work. Look I'll call you in the morning okay? Yeah it's all good. Yeah bye."

Casey settles back down into his original position, not wanting to indicate that he had overheard the conversation but somewhat comforted that he wouldn't face the entire night alone in his condition. "Look if you have a date…"

"Family stuff…no big deal. How's your head?"

"Hard as ever," Casey retorts as he tries once again to slowly sit upright; this time resting against the cool concrete wall and closing his eyes to allow the dark circles to dissipate. When he opens them the notices Severide looking at him in concern. "What?"

"Nothing. You ready to go?"

"Look Kelly…"

"Hey only my mom can call me that," Severide smirks. "Damn girl's name."

"You can change it," Casey shrugs as he slowly slides closer to the bed edge and remains still a few seconds longer. Next he manages to get onto the floor, holding onto the edge of the bed to steady himself, his heart starting to beat a bit louder and forcing blood to rush back to his ears. "Damn," he gently curses but remains in place.

"Come on," Severide urges as he gently takes Casey's left arm and helps him to the door. "I'm done carrying you."

"I'm not that heavy."

"Dead weight," Severide teases as he feels Casey pulling away from his grasp. "Fine but if you fall down…"

"I need a copy of the Coroner's report. If they gave it to Duncan's wife and she didn't share…"

"Then let them deal with it."

"He came after me…he blames me…I need to fix this," Casey insists as Severide mutters under his breath but follows him toward the Chief's empty and quiet office.

"Being here like this feels like…"

"We just broke into the principal's office?" Casey adds with a small smirk. "Yeah it does."

"Just get what you need."

A few moments later, they reemerge into the main bay with a copy of the report in hand, slowly heading for the exit doors to the parking lot, Casey trying his best to get his vision to fully refocus so he could drive on his own. But instead of heading for his truck, he offers a mild protest when Severide gently steers him toward his own waiting car.

"I can drive…where are my keys?"

"I have them. Just get in. I'm not calling my guys in to deal with something you might be responsible for," Severide states firmly. "I'll keep them until I feel you're ready to be set loose on the public again."

"Very funny," Casey deadpans as he slowly gets into the front seat of Severide's car; actually thankful that his brain didn't have to worry about himself, a moving vehicle and the public at large in his way on the road. The drive over to Vincent Rhimes is spent in silence, Severide glancing over every few seconds and noticing in concern Casey trying his best to keep his eyes open and clear.

"Okay…here we are," Severide announces quietly as they pull to at stop before Vincent Rhimes small home. "Ready?"

"I can do this on my own."

Thinking Severide will just stay put, Casey slowly gets out of the car, hoping to just show Vincent Rhimes the report and leave; wondering how his attacker would react to seeing him standing at his doorstep with no police at his side. But Severide doesn't stay put, merely falls into a slow step behind Casey and praying that the incident doesn't turn violent once more; not sure Casey's frame would handle another direct assault.

Casey holds his breath, actually thankful that he isn't alone; the door slowly opening and Vincent Rhimes looking at him in utter shock.

"Before you say anything…I thought it fair you know the truth – from me."

"I know your damn truth and I don't want IT!" Rhimes shouts, Casey's frame instantly stepping back a foot and seizing; his brain racing for a counter move incase Rhimes wanted to get physical again.

"Your sister in law got the report and didn't share it right?"

"It's none of…"

"Hey look," Severide pipes up. "My friend here was dealt a pretty unfair advantage at your hands. I saw you and your friend in the parking lot but was talked out of calling the cops with an assault charge on you by this man. He has the truth for you and I'd suggest you listen."

"The coroner's report confirmed what my men discerned; he was dead when they found him. The fire closed in behind them faster than expected and they had to move on; there wasn't time for them to go back for his body until after everything was put out," Casey explains as he shoves a copy between Rhimes slightly open doorframe. "Just read it. It wasn't me. If he was alive…he'd be here…we would not have left him, I give you my word."

And with that he turns and slowly makes his way past Severide, not expecting anything from Vincent Rhimes at the moment and wanting nothing more than to get home and just pass out, putting his pounding head to rest for the remainder of the night.

"I woulda pressed charges," Severide offers Rhimes a last heavy frown before he turns and hurries after Casey, catching up to him as they both get back into the warm cabin of his car.

"Think he'll care?"

"Actually…yeah I do," Severide mentions as they both turn and watch Rhimes give them both a nod and then disappear into his home. "Just some guys can't say it you know?"

"Actually…yeah I do," replies softly, his eyes kept straight ahead.

Severide starts up his car and pulls away, about ten minutes later glancing over to see Casey almost fully asleep and knowing if he takes him home that he might end up falling down the stairs or something else that would add to his current injury-impaired state. So instead he turns left and heads for his own loft apartment.

"Where…are…we," Casey mumbles as his freshly pounding head tries to confirm his present location. He looks at the underground parking lot before he watches Severide come around to his side of the car and gently help him out, his arm being put around Severide's neck to help him walk; his body moments away from shutting down for good.

"Dead weight," Severide tosses lightly as they head for the elevator, Casey's system shutting down a bit faster than both had expected. "Just don't pass out….in here…great," he struggles to keep Casey upright in his grasp as the steel box moves upward. He fumbles with his keys as they near his apartment door, lightly cursing as he pulls Casey's instead of his own and gently knocking; being greeted by his very surprised room mate.

"Okay…"

"I picked something up on the way home," Severide grunts as he literally drags Casey's now sleeping frame into their apartment.

"Should I ask?" Shay asks in wonder, looking at her roommate in wonder as she closes and locks the door.

"No," he remarks as he gently places Casey's frame down onto the soft sofa and then stands back up and looks at Shay. "What?"

"Oh nothing…just that you brought home someone most of us think is your biggest rival and what the hell happened to him anyways? A fight? Casey was in a fight? With you? Are you responsible for that black eye and busted lip?"

"No. Long story, but he was looking all pathetic and passed out in the car. What was I supposed to do? Leave him in the parking lot at work?"

"He was jumped?" She asks in surprise.

"He was."

"You coulda dropped him at Hallies?" Shay offers.

"He wanted to go home – alone."

"And when he wakes up and isn't at home?"

"He will be fine. It was better than him falling down the stairs or something," Severide explains in his defense.

"Right. You know while you two act as outward rivals, I think secretly you're good friends."

"Hardly," Severide retorts with a small laugh as Shay folds her arms over her chest and looks at him in suspect; forcing him to continue. "I respect him…most of the time, okay? Look I couldn't leave him like that. Okay?"

"Okay," she shrugs as she pats him on the shoulder and turns to leave. "Funny thing…he probably would have done the same for you."

Severide watches her take her leave and head upstairs, turning back to Casey's now sleeping form and slumping down into the chair opposite and looking at him with a frown. "Yeah…he probably would have," Severide whispers in acknowledgement as he leans back and rests his own pounding head for a few moments and then looks back at Casey before he knows its time to turn in as well and bring the tense and trying day to a muchly needed close.

"Night…Matt," he whispers as he turns off the light, bathing the room in darkness and not hearing Casey whisper 'g'night…Kelly' in return.

THE END!

A/N: well? Was it entertaining? Did you like it? Want more from our boys? I really do want to try a longer, multi-chapter story and am working my way up to that with these smaller ones. So please let me know your thoughts before you go and thanks so much in advance!