AN: This wasn't supposed to be my first Eureka fic, but a terrible pun for a title and my own need to fanfic fix the loss of the Mars rover compelled me to write it. Don't get hung up on where this fits in canon as I'll just claim this is an AU Timeline cause by some Time Lab mishap. Totally plausible, huh? Fic prompted by a Tumblr post about Opportunity that resonated with me.

This fic is dedicated to this amazing fandom who stays alive and producing great content even though this show hasn't been on in years. I love you all for all the amazing works that I have been able to devour as I jump into this fandom WAY too late.

A Stark/Carter fic, because good lord what an amazing OTP.

Opportunity Knocks

Chapter 1

Knock Knock

My battery is low and it is getting dark.

There was something so hauntingly human about the last communication from the Mars rover Opportunity that even Jack Carter had to admit he had felt a pang of sadness for the little space robot. The posthumous accolades of accomplishments didn't help matters either, that always seemed to be a 'celebration of life' that came too late for the recipient. He, himself, wasn't even aware NASA lost communication with the rover almost 8 months ago until he arrived at Cafe Diem today to a sober atmosphere. Today NASA finally gave up on trying to hail 'Oppy' and declared the mission over. You could hear crying as you passed by people on the way to the counter, candles were lit on a memorial display on the back wall and there was a notification for a proper send off at Cafe Diem later that day.

Normally Jack would appreciate the quiet, it was a rare day where the banes of his existence were too preoccupied to blow anything up. Unfortunately his first instinct was to go to GD after taking possession of his morning Vinspresso and learning about the 'funeral' being held after work. Not because he worried about impending chaos from someone setting off a doomsday device in order to go save the robot, but because he couldn't shake the memories of Nathan Stark's tear filled eyes when he lost Callister.

Talk about the bane of his existence.

Nathan Stark, the textbook definition of tall, dark and handsome with a Eureka twist; brilliant beyond measure, confidence and body of a God and a smirk that could melt anyone from the inside out faster than radiation. Jack had come to terms with his infatuation with the man a year ago, settling for the playful banter and save-the world teamwork, as Nathan was still married to Allison. Never mind that he was well out of his league, but Jack protected his heart from shattering by just telling himself that Nathan was a married man.

That didn't stop him from going to GD to exclusively check on him, because he was concerned for him. His heart ached for him and he needed to know he was OK. He knew that Stark had been involved in the rover projects and knew that the artificial intelligence programming had to come from his mind. He knew all that before S.A.R.A.H had informed him of the news this morning, she cleverly and not-so-subtly, had locked on to his heart rate increase, pupil dilation and vocal cord constriction every time Stark showed up at his door. He knew it before running into Fargo at Cafe Diem who started sobbing when he shared the news and mentioned he was taking care of the funeral arrangements and that he hoped Stark would speak because he doubted he could manage it. Jack knew, because he had learned to stop being surprised by everything Nathan had his hands in creating and just appreciated that the guy he fell in love with was one of the most capable and amazing people on the damned planet.

The bane of his existence was right, because everyone else paled in comparison to Nathan and he just was happy to settle with basking in his glow. It was as close as he was going to get and he was OK with that.

So he made his way through the quiet foyer of GD, listening to sniffling and sobs and the sound of shoes clicking on the marble floor. He focused in on the familiar sound of footfall and looked around for Allison who had a very distinct walk. He also could tell she was pissed off from the cadence of her steps and typically that was a by-product of the Director being in a fowl mood. So he followed the sounds down the mostly empty hallway and saw her go into her office. It never hurt to get a feel for the situation he was walking into, it gave him a chance to thicken his skin in case Nathan was cranky enough to weaponize his words. "Hey, Allison."

"Jack, I wasn't expecting to see you today." Allison said as she dropped some files on her desk and gave him a smile. " I thought you'd have an easy day today considering half this facility is in mourning."

"I was actually just stopping in as a preemptive strike." Jack said and leaned on the door frame. "Emotional scientist are usually the cause of my bad days."

"Don't worry, most of them aren't even working today." She said and sat down.

Her annoyance was evident. That couldn't be good. "Is it a holiday or something?"

"It might as well be." She pulled up a list of personnel who had decided to use a personal day or who's labs were reporting a decreased amount of usage. She showed him the growing list.

Jack gave her a characteristic smile. "That's actually good news for me."

"Enjoy it while it lasts."

Jack rubbed his neck and said, "So, is your husband on that list? Fargo mentioned something about hoping he would give some speech at the funeral tonight, he sounded concerned that he wouldn't show. That just sends up warning signs about Fargo pressing buttons or doing something...Fargo-ish."

Allison curtly replied. "No, he's here. He's been here since communications ceased eight months ago. He's been married to that robot more than me, so last month he became my ex-husband."

Jack felt like the air had been sucked out of the room. This was the first he had heard of this. Not that he really pried into Nathan and Allison's personal life, he actively tried not to, but Eureka was terrible at keeping secrets. They had to have done that quietly for nobody to know about it. "Are you OK?"

She gave him a smile, Jack always was so quick with concern for others. "I'm fine. It's a relief, actually, knowing that I didn't make the wrong decision the first time. He hasn't changed. His work will always be his first love and honestly I gave him enough of a chance to put his family first. As soon as Opportunity's communications went dark he was preoccupied. Then the dust storm cleared and attempts to hail the rover fell on deaf ears and the old Nathan returned. Or, didn't return, from work. Sorry I didn't tell you, I've been processing it all myself. Hoping that maybe it would feel more emotional, instead it's just fact."

"Sorry Allison, if you need anything you let me know." Jack nodded. He had never really understood them. They loved each other, that was clear, but Allison seemed to like to keep her distance from Nathan at work. He didn't complain, that gave him the chance to spend a lot of time with Nathan doing their save-the world thing, but it seemed like a missed opportunity for Allison to spend time with him. Of all the people who could help matters, it should have been another brilliant doctor not Sheriff 111. Instead she took the 'just fix it' hands-off approach and only helped when it was within her area of expertise.

"Thanks Jack."

He normally wouldn't accept that as a way to bow out of the situation but his mind was screaming at him. He needed to excuse himself and go check on Nathan because he was sequestered in his lab or office and hurting. So he quietly left the doorway and let her get back to work and put his hands in his pockets to approach Nathan's office. He walked slowly and collected his thoughts because he knew that this new information didn't change anything, but his heart-rate picked up as he soon as he saw Nathan's name on the plaque on the door. He looked at Fargo's empty desk and pulled a hand from his pocket and knocked.

"Come in."

Jack walked in and saw Nathan somewhat disheveled for him, at least first thing in the morning. His vest and jacket were hanging up on the wall and he was sitting at his desk with his sleeves rolled up and staring at a computer screen. He looked like he hadn't slept. So he walked over and set his cooling Vinspresso down on his desk, he hadn't touched it since he picked it up at Cafe Diem, as it seemed better used as a peace offering. "Are you doing alright?"

Nathan leaned back in his chair and looked at Carter, his soft blue eyes and expression of concern the first bit of warm interaction he had had this morning. He wasn't alright, but he wasn't going to admit that. He looked at the coffee and gave a tired smile, it was a nice gesture. "I assume you heard about Opportunity."

"Yeah, flags are flying at half mast." Jack leaned against Nathan's desk, wanting to get closer to the other man and lend some support. "Red flag for me. Your people don't handle emotions well."

"Ally send you in here?"

Jack opened his mouth to say something and Nathan shook his head knowing that wasn't the case. God, he struck a nerve with that.

"Of course not. She wants to send me to Mars and strand me there."

"That's... harsh." Jack said and Nathan's unguarded eyes flickered up to him and he saw a glimpse of the pain he had been dealing with alone. Jack didn't want to take sides, but he had been the one who was on the same end of this deal with Abby. Always hearing how work took him away from his family, never getting the support for his life's work that she was expecting him to give in return. It was messy, there was no right because both parties were wrong, but he couldn't help but sympathize. "However, if she has some special project laying around that can send you to Mars, let's go get your robot."

Nathan covered his mouth with his hand to hide the smile Jack's simple statement and bravado caused to form on his lips. Leave it to Carter to boil the situation down to 'Well, let's just go pick it up and bring it home so we can dust it off ourselves'. He took his hand away from his mouth and reached out for the coffee. "It's not my robot, I just..."

"Designed most of it, like you always do." Jack said and watched Nathan's eyes sparkle. Despite the massive ego and frightening levels of pride this man housed in his giant brain, he still had human insecurities. Jack had to look away because the look he was getting was warm and warming him more than he felt himself capable of hiding from scrutiny.

Nathan took a sip of lukewarm coffee and realized this cup was not originally intended for him. He just looked like shit and looked like he needed some second hand caffeine. "She was only supposed to last 90 days. I should be proud of how long she survived."

it took Jack a moment to realize they were not talking about Allison. He glanced back at Nathan. "However she's out there alone and cold and just needs some help to keep going. I get it. It was a distress call."

Nathan took a deep breath. That's why it hurt. Leave it to Jack to take it down to the raw components.

"This is also Eureka, so you can't tell me that we don't have some device that can go to Mars and help her." Jack said, compelled to keep talking as he heard the painful, emotional breath Nathan had exhaled. "Some kind of...interplanetary windshield wiper...device."

Nathan had just taken a sip of coffee to cover his emotional distress and almost choked on it when Jack said that. Now he was having to grab tissues and blow coffee out his nose. "Jesus Jack..."

Heard him say his name with a little bit of mirth, well that was enough to encourage him to keep throwing out ideas. He slipped off the desk and turned around to lean on it and spit out whatever came to mind. "An emergency space blanket with heating and cleaning capabilities. Hell, I'm sure there's a space ship somewhere in this building! Just attach one of those grapple hook things they have on those arcade games with crappy plush toys. Trade Area 51 for something we can use. Oohh...give them Fargo!"

"Carter..." Nathan couldn't hide his smile now.

"Fine, I'm just trying to cheer you up." Jack admitted and saw another look of raw emotion he wasn't prepared for. "However I'm serious about going to get the robot. There has to be something here at GD that can do that."

"We can't launch a space expedition to fetch an expendable rover from the surface of Mars." Nathan had to say it. He had to say it out loud to make sure he didn't get swept up in Jack's playful determination.

"Someone here has a project that needs to be tested." Jack said and knocked his fist on the desk. "Opportunity is knocking, let's send these damned scientists to some other planet to test out their disastrous experiments and get it out of my jurisdiction for once."

Nathan held onto his gaze longer than he should have, but there was something so very pure and infectious about Jack's enthusiasm. It's why they made a good team, he had the knowledge to make it happen and Jack always brought the passion and perseverance. If only Ally could muster up a fraction of... his interest. "Jack, why do you care so much?"

Jack finally ran out of words. He found himself just lost in Nathan's observing eyes and couldn't help but feel a little naked. It wasn't his standard operating procedure to encourage Eureka's scientists to unleash their untested experiments and he had barely tolerated Zoey's robotics projects, so what the hell did he say? "Because we couldn't save Callister."

Nathan swallowed hard as he poked the never healing wound on his heart. He saw that Jack didn't want to bring it up, but that had to be what compelled him to come check on him in the first place. It wasn't the same, Opportunity was no where near the advanced level A.I. that Callister was, but it didn't mean he was just going to give up. Too many regrets already. "I don't know where to start."

"What about that FTP drive?" Carter said. "Fargo was talking about that when Opportunity first went offline."

"FTL, Carter." Nathan said and cleared his throat. He felt that stir of familiar excitement that overtook him when he and Jack did their thing and saved Eureka. Jack's simple suggestions always lead down a road to a solution and Nathan had to admit he had fun traveling that road with him. Science without the inhibitions, science with the excitement that it used to hold when it was only about the work. So he leaned forward and started to search the GD database for project information. "Faster than Light drive."

"That could get us there, right?" Jack asked. "He said we were planning to go to Titan which is a lot further away than some little red planet next door."

"Planning to go to Titan in a few years." Nathan said.

"Sounds like a great time to test it out." Carter said and gave Nathan a shrug. "I mean, safety right? You have to make sure you can send and retrieve objects back and forth before you commit to sending people. Right?"

Nathan gave him one of his smirks that said, 'not really, but if it makes you feel better, than sure!'.

"Right?" Jack repeated, wanting to hear that Nathan did value human life as much as he valued his artificial ones.

He left him hanging long enough, he liked teasing him too much. Jack always got an adorable look on his face when he was concerned about his humanity. "Yes, we do intend to test it before using it on people. However, it's years from that point."

"This is Eureka, we condense years of work into an afternoon in order to save the world every week."

"This is hardly an emergency." Nathan said and flipped through the project folder to see that the FTL drive was barely in infant stages right now. "I can't divert funding and hours for this. I can't make it priority, especially when Opportunity is not even our property."

"I guess it's good that half the scientists in this place took a personal day to mourn the Mars rover, huh?" Jack watched Nathan's eyes light up again. He had to admit at some point that he was becoming addicted to that reaction, but for today he was not ready for that revelation. "Bonus that NASA publicly announced it's abandoning Oppy today."

"We're just taking an opportunity to pick up some space junk." Nathan said, getting on board with Jack's line of thinking.

"Space junk has already rained down on Eureka like a thunderstorm of trash. We can use that project of Megan Harrington's maybe?" Jack shrugged. "Just another day in Eureka, might as well order up something you want instead of a orbiting toilet."

"I'll be damned, Jack." Nathan mumbled. "We can do this."

"We always find a way." Jack said and couldn't resist a pun. "Opportunity is knocking."

Nathan knew he was beyond exhausted when he actually laughed at that. "OK, get Fargo and tell him what we're doing. Don't tell Ally, she's already mad enough about all this."

"Maybe you should come to Cafe Diem and explain it yourself." Jack said. "It's where all your scientists are hanging out already, decorating and lighting candles. They're playing a slideshow movie of Oppy's exploration photos set to 'Dust in the wind'. Fargo wanted a speech, go give it to him."

Nathan smirked and then realized he looked like he had been living in his office for a week. "After I shower."

"Wear black, it's a funeral." Jack's tongue got past his mental filter and he added, "You look good in black."

"I look good in anything," Nathan winked. "Or in nothing."

"Yeah, probably not the kind of persuasive we need right now." Jack had to clear his throat and Nathan slapped him on the arm before getting up to go to his personal bathroom and get ready to drop a bomb on the unsuspecting mourners at Cafe Diem. Apparently he was going to start by hitting Jack first, as that was enough to send his heart racing and his thoughts directly into the gutter. What the hell? The door shut to the bathroom and Jack leaned on the desk and focused on the problem at hand and not Nathan's confusing words.