A/N: I finally got the chance to stream the Season 6 finale a few days ago. This is what came out of it.

When Felicity Smoak was having a bad day, which was most days lately, she would think about her husband and wonder whose prison was worse; hers or his. Then she would immediately kick herself for being a wuss. After all, everyone referred to her prison as protective custody. She had decent food, a comfortable place to sleep, and most of the amenities she was accustomed to. Oliver had a thin bunk and was surrounded by psychopaths who wanted to kill him. Physically, there was no comparison. And her prison was finite; it was expected to end when Diaz was captured and she was no longer being threatened. Oliver's prison was anticipated to last – if not for the rest of his life – then at least for a couple of decades.

On the other hand, Oliver had chosen his prison while she'd had no say in hers. He'd assessed the situation with Diaz and decided that the best thing for everyone was to out himself as The Green Arrow and then surrender to the FBI. In return, he'd obtained immunity for The Arrow's associates and a commitment from the FBI to pursue Diaz until the man was neutralized. (Felicity hated the expression neutralized. Neutralized is what happens in chemistry when you mix an acid with a base. Diaz was either going to be killed or locked up.) At any rate, Oliver had been able to prepare himself mentally for his prison. Felicity had not.

She couldn't decide what stung the most; that Oliver had kept another secret from her, that he'd treated her as if she were one of his associates instead of his wife, or that he'd yet again made a huge, life-altering decision without talking to her. It really didn't matter. What mattered was that he'd unilaterally determined that Felicity, at the age of twenty-seven, was going to be a single parent, destined to sleep alone for a very long time. Which really meant that her prison wasn't so finite after all; it was going to last as long as his, regardless of what happened to Diaz. Because what did Oliver think she was going to do while her husband was behind bars? Fall in love with someone else?

On days when her sense of humor wasn't failing her, she had to smile at the irony of the situation. Three years ago, her happy engagement to Oliver had fallen apart because he hadn't trusted her with the news that he had a son. Now, her happy marriage to Oliver was in limbo because he'd done what he'd thought was necessary to ensure that she could raise that son. He'd gone from keeping William out of her life to making William the center of her life – and had never once asked Felicity how she felt about either. But that was Oliver; once he made his mind up, it didn't occur to him to consult anyone.

All of which made it sound as though she resented William – which couldn't be further from the truth. She loved the kid, and she loved the fact that Oliver wanted her to be the one to raise him. Keeping William healthy and happy made her feel as though she could still do something for her husband. She liked to think that the weekly communications she and William sent Oliver – William's academic progress, his recent growth spurt, her latest cooking debacle – gave him something to smile about. However, it would be a lie to say that caring for William didn't depress her at times. There was a lot of his father in him; and when he stubbornly locked his jaw or obsessed over some imagined failure, Felicity would feel a wave of longing for Oliver that was so strong she had to shut herself in her room and cry for a little while. Afterwards, she would dry her eyes and do her best to pretend that nothing had happened.

It didn't take long for her to realize that things were as tough for William in protective custody as they were for her. There was no one his age at the ARGUS facility. Felicity was pretty much his only company, which meant that she had to fill the roles of teacher, mother and friend, sometimes trying to be all of them at the same time. It helped that William shared her love of learning. They spent hours with his books and Felicity was certain he was going to be at least one grade ahead of his peers in math and science when he finally returned to school. English and history were a different story. They had never been her favorite subjects, and while she did her best to summon the proper enthusiasm for Shakespeare, she was pretty sure that William saw through her. Still, through his own determination, he was at least treading water in the humanities.

As happens with all major life changes, old habits were replaced with new ones quicker than anyone would have anticipated. Felicity and William settled into a weekly rhythm of living in protective custody that included study, exercise, leisure, plus a little work for Felicity when ARGUS was forced to admit they could use her expert computer assistance. Felicity and William sometimes had dinner on Saturday evenings with the Diggles, but didn't encourage visits from the rest of the former team members. Felicity couldn't help thinking that she wouldn't be in this place if the new folks had stayed with Oliver when he'd first needed their help to defeat Diaz. And immunity wouldn't have been necessary if Rene hadn't betrayed Oliver to the FBI in the first place. Oliver may have done his best to mend fences before he went to prison, but Felicity didn't feel the same obligation.

They never explicitly discussed it, but somehow she and William also established a set of rules for how often they would speak about Oliver. While it sounded loving to say her husband was always in her thoughts, Felicity found it helpful to have periods of time when she didn't think of him. She felt a little guilty about that, but then reminded herself that she needed to stay healthy for William's sake; and there was nothing healthy about continually dwelling on something you couldn't have. William must have felt the same, because they fell into a routine where they talked about Oliver in the morning over breakfast and in the evening before they turned in for the night. In between, they did their best to focus on William's studies, current events, and some form of amusement. There were days when they were fairly successful. And there were days when they couldn't help but think about him more often.

It was odd, the things that would trigger thoughts of Oliver. Some were completely logical; like news of the interim mayor in Star City. Others were silly; like the bland, white cheese on their sandwiches reminding them that Oliver always made his grilled cheese with gourmet Swiss. Oliver even intruded one morning when Felicity was giving William a math lesson.

They were talking about pi.

"The textbook says pi is an irrational number," William said, pointing to one of the pages. "What does that mean, exactly?"

"It means that it can't be expressed accurately as a fraction," Felicity replied. "You know how one over two – or one half - is exactly the same as point five? You can't do that with pi. It starts as three point one, but the numbers after the decimal point never end; they go on forever and ever. There's no fraction that's the exact equivalent."

William frowned. "Is that important?"

Felicity shrugged. "One of the things computer scientists like to talk about is how fast a new computer can calculate pi to billions of decimal places. But that's kind of a party trick. What's really important about pi is that it's a fundamental constant. It's the ratio of a circle's circumference to its diameter – and it has the same value for every circle that ever existed, no matter how big or small." When William didn't say anything, she continued, "It's pretty cool, when you think about it. It works for a penny, it works for a tire, and it works for a planet – assuming the planet is perfectly round – which the earth really isn't, it's an oblate spheroid – but, you get my point."

William nodded. "Fundamental constant," he repeated.

"There's several fundamental constants in physics," Felicity went on. "The speed of light is one. It's the same everywhere in the universe. And all electrons have the same weight – as do protons. And one of my favorites is the fact that all objects on earth fall at the same speed, no matter how heavy they are. Well, they do in a vacuum, anyway."

William nodded again.

"I always liked the idea of fundamental constants," Felicity said. "You can count on them to be the same, no matter where you are or what's going on. They're consistent. They can't be changed."

William smiled. "Kind of like Dad," he said dryly.

Felicity raised an eyebrow. "What do you mean?"

William shrugged. "Just that you can always count on Dad to do the same thing when stuff hits the fan. He'll go off on his own and try to fix it. Doesn't matter what it is." His smile faded as he watched Felicity's face. "Did I say something wrong? I said stuff. I didn't use the s-word."

Felicity hastily shook her head. "No, you didn't say anything wrong," she replied. "That's an…an astute observation." She forced herself to laugh. "But I don't think your dad's exactly a fundamental constant. I know he can be pretty stubborn sometimes, but he can change. It just takes a little work and persuasion from the people who care about him."

William studied Felicity for a few more seconds and then smiled again. "More like a lot of work."

She forced another laugh. "Right. A lot of work."

They continued the math lesson and didn't speak of Oliver again for the rest of the day.

Later that night, when Felicity was lying alone in bed, she thought about what William had said. When stuff hits the fan, he'll go off on his own and try to fix it. The kid wasn't wrong. For as long as she'd known Oliver that was exactly what he'd do. He'd involve her and John up to a point, but then eventually make his own decision and not share it until the last minute – if at all. And that decision usually included him doing something solo. He'd gone to Lian Yu after the Undertaking, he'd run away to offer himself as a sacrifice to Slade Wilson (which they thankfully had been able to stop), and he'd devised a plan to defeat Ra's al Ghul without talking to either her or John. He'd even decided most recently that he wanted to go back to being The Arrow - alone. His decision. His plan. No discussion.

Well, she thought, you knew what he was when you married him.

A fundamental constant.

It turned out the FBI wasn't as good at neutralizing Diaz as they'd thought they'd be. For a couple of weeks the Feds insisted that Diaz had died from his fall and spent precious time searching the waters around Star City for his body. By the time they admitted that he was alive and had escaped, Diaz was in the wind.

The FBI then argued that the chances of Diaz coming after Oliver Queen's family were small. The crime lord had most likely fled somewhere far from Star City, they said, and it should be safe for Felicity and William to go back to life outside the ARGUS facility. But Lyla Diggle would have none of it.

"I can't imagine facing Oliver if anything happens to you or William," she said to Felicity. "I know you're tired of protective custody, but you're going to have to stay here until Diaz is dead or locked up. I'm not going to take any chances."

Felicity reluctantly agreed. At least Lyla had said dead and locked up, not neutralized. And Felicity couldn't imagine facing Oliver either, if she allowed anything bad to happen to William.

So they hunkered down at the ARGUS facility, and the life in protective custody that had been expected to last a few weeks stretched out into several months. The situation meant that Felicity and William spent a lot of time together; the sort of time that either bonds people for life or eventually makes them detest each other. Fortunately, Felicity and William bonded. From her perspective, William was an easy kid to love. He was kind, perceptive and grown-up for his age. So grown-up that, at some point, it occurred to Felicity that William was playing multiple roles for her, just as she was doing for him. He was son, student and trying his damnedest to be the man of the family. She hoped the situation wasn't robbing him of his childhood entirely.

Eventually Lyla relented on security – a little - and allowed Felicity and William an occasional trip outside the facility to see a movie or go shopping. She assigned an agent named Jackson Taylor as their personal security guard and he patiently escorted them on outings for school supplies, shoe shopping (for Felicity), and even one afternoon at a trampoline park. When Lyla had first introduced Jackson, Felicity had been taken aback. The bodyguard was dark-haired, attractive and fit-looking, but not physically imposing; he was about five-nine or five-ten, and she guessed that he was younger than her. Not to mention that he stammered nervously every time he tried to talk to her.

"Are you sure this guy has experience?" Felicity had asked Lyla, when the introductions were over and Jackson had headed off to the ARGUS gym. "He looks very young and he can barely get two words out."

Lyla had smiled. "He may not have a lot of experience with pretty women," she'd replied, "but he's outstanding in hand-to-hand and he keeps his head when the bullets start flying. He'll take care of you, trust me."

Felicity had nodded. "Okay."

"Besides," Lyla had added, "I don't think Oliver would be too happy with me if I gave you a real charmer for a bodyguard. Better to have one that's a little shy."

Felicity had laughed, something she hadn't done too much of lately. It felt good.

Jackson may have been tongue-tied around her, but he clearly felt more at ease with William because he began spending time with the boy, even when his services as a bodyguard weren't required. They played video games together and Jackson taught William how to shoot a basketball and throw a baseball.

"Do you mind, ma'am?" he'd asked Felicity nervously, the first time she'd gone searching for William and had found the two of them on the basketball court by the ARGUS gym.

She'd shaken her head. "Not at all. You two looked like you were having a good time. Do you have kids of your own, Jackson?"

He'd blushed. "Not yet, ma'am, but I certainly hope to one day."

"Something tells me you'll make a great father."

His blush turned a shade deeper. "Thank you, ma'am. And if you don't mind me saying so, I think you're a great mom. Will's a lucky kid."

Apart from the fact that Jackson insisted on calling her "ma'am," Felicity genuinely liked him and was grateful he wanted to spend time with William. Being with Jackson gave the kid the chance to be a kid and to ask questions that a boy nearing adolescence might not want to ask a woman. This felt more important than ever, since the FBI continued to restrict their opportunities to communicate with Oliver.

Right from the first day, the Feds had told Felicity that she and Oliver would not be allowed to email each other. They didn't offer further explanation, but Felicity was certain they were afraid she would send him malware that could disable the prison's security systems and give him a chance to escape – which, in all fairness, is exactly what she would have done. (She had to give Special Agent Watson credit for brains on that one.) She and William were permitted to send Oliver one manila envelope a week with letters and photos. She was willing to bet that every envelope was inspected carefully before Oliver received it.

They didn't get the chance to actually visit Oliver until more than two months after his arrest. She presumed the FBI dragged its feet because their lack of progress finding Diaz meant the Feds hadn't lived up to their end of the bargain. Oliver had turned himself in, but Diaz was still free. Oliver wasn't going to be happy to hear from Felicity that she and William remained in protective custody, with no end in sight. It was a sign of the respect the FBI had for Oliver's skills, Felicity thought, that they were worried about his reaction, even when he was behind bars.

Felicity was also worried about her first visit with Oliver, but for a whole different set of reasons. She knew the inmates would have it in for The Green Arrow and she was frightened she might find him bruised and bloodied. She was also concerned about his emotional state. He'd seemed so resigned - almost numb - when they'd said their goodbyes; as if all feeling had been drained out of him. If he was still like that, if her visit didn't bring him any kind of happiness, then she wasn't sure she could keep going to see him.

Given that Oliver was in a super-max facility, she expected that she and William would not be allowed to meet with him face-to-face. She figured he'd be on the other side of a wall and she'd have to use a phone, the way she'd seen prison visits conducted in so many movies. But to her surprise, when they got to the prison, they were escorted to a large room with a half a dozen heavy metal tables, widely spaced and bolted to the floor. Her heart started pounding when she saw that Oliver was seated at one of the tables. He shared the room with a couple of guards and one other prisoner; a bald man with a skull tattooed on the top of his head and biceps the size of Felicity's legs. Skull-Head was seated at the table the farthest away from Oliver, talking to another man.

She noted immediately that the super-max facility was living up to its reputation. Oliver's wrists were shackled to the table and his ankles were shackled to the floor. A guard stood five feet behind him, with a heavy wooden baton in his hand. She did her best to ignore the guard as she headed straight for Oliver's table with William at her side. Jackson, who had escorted them from the ARGUS facility to the prison, waited near the doorway. Oliver watched her approach, his eyes never leaving her face. She thought she saw those eyes light up for a second – but then they immediately became unreadable.

"Oliver," she breathed, reaching across the table to take his hands.

The guard slapped the baton against his palm, and Oliver slowly shook his head.

"We're not allowed to touch," he said gently.

"What?"

"We're not allowed to touch," he repeated. "They don't want to risk you slipping me anything."

She felt tears begin to fill her eyes, as much due to frustration as from sadness. After all this time, she wasn't allowed to even hold his hand? "I had to leave my purse and phone at the check-in area, I went through two metal detectors, and I was frisked," she said. "After all that, we still can't touch?"

He gave her a small smile. There was no happiness in it. It was a smile that said, what can you do?

"You look good," he said quietly. His eyes moved to William. "Both of you look good."

Felicity felt butterflies of fear flicker in her stomach. This was the same Oliver she had seen when they'd said their goodbyes two months ago; subdued, resigned. She tried to force a little cheer into her voice. "You look good, too," she said.

It was almost true. She had been afraid that she would find him covered in wounds and scars. There were a few yellow bruises on his face, but they looked old and he appeared healthy overall. A little thinner than she liked to see, but still fit and strong. She guessed that he had a lot of time for pushups and sit-ups in his cell.

"Was it bad?" she asked, meaning; did the other prisoners beat up on you badly? She didn't want to ask the question explicitly in front of William.

Oliver understood. "Not too bad," he replied. "There were a few differences that we needed to work out when I first got here, but I think we've resolved them. Everyone pretty much leaves me alone now."

"That's good." And I trust you beat the crap out of them when they came after you.

Oliver turned to William. "Thanks for all the letters, buddy," he said softly. "I look forward to them every week. Although I have to admit it sounds like you've passed the point where I'll ever be able to help you with schoolwork. You certainly didn't inherit my study habits."

William smiled proudly. "Felicity says I'm almost ready for high school math."

Oliver nodded. "That's fantastic. I just hope she's leaving you time for a little fun, too. Math is important, but so are other things."

Oh, Oliver, Felicity thought.

William's smile faded. "Felicity's doing great, Dad," he said, a little defensively. "She takes good care of me and we do other things besides studying. We play video games."

Oliver leaned forward and studied his son. "Do you get the chance to run around a little – be active?"

"I've been playing hoops with Jackson," William said. "I can sink a free throw now."

Oliver sat back in his chair and his gaze shifted to Felicity. After a pause, he said, "William, can you give Felicity and me a minute?" His tone suggested no wasn't going to be an acceptable answer. In a weird way, it almost made Felicity happy, because he sounded more like the old Oliver.

William looked at his father. "Okay," he said. He got up and walked over to the doorway.

"He's protective of you," Oliver said to Felicity, once William was out of earshot.

She shrugged. "We're protective of each other," she replied. "We spend a lot of time together, especially since he can't go to school right now. We're each other's support system."

"And Jackson? I don't remember him in any of the letters."

She tilted her head toward the doorway, where the bodyguard was standing and now talking to William. "Jackson is our personal security guard for days when we're allowed off the ARGUS facility. He also spends a little of his free time with William and they do guy-stuff – shoot baskets, watch sports on TV – things that aren't exactly my forte." She cringed inwardly right after the words were out. She'd pretty much told Oliver that Jackson was doing activities with William that a man normally did with his son.

But Oliver didn't appear upset. He stared at Jackson. "He's your personal protection? He looks like he's eighteen."

Felicity shrugged again. "He's twenty-five and Lyla says he's very skilled."

Oliver turned his gaze back to Felicity. "And he's good with William?"

"Yes. They get along well."

"And what about you? Does he get along well with you, too?"

Felicity searched his tone for undercurrents of anything – anger, jealousy, suspicion – and heard none. So, she replied matter-of-factly, "We do okay. He's nervous around me and doesn't say much. And he calls me ma'am, which makes me feel old."

Oliver grinned – a genuine grin this time, not a sad or ironic one.

"But," Felicity continued, "he does take me shoe shopping, which is something you would never do. So that puts him kind of high on my list."

Oliver chuckled. "I never had the stamina for that."

Felicity was pleased. It was good to see a spark of life in his eyes.

But then he quickly sobered. "I hope you understood what I was trying to say before, Felicity. I'm glad that William's doing well academically, but I want him to have fun, too. I don't want his childhood ruined because his dad's in prison."

Felicity's face grew warm. Oliver's words sounded a little like criticism. "I'm doing my best, Oliver," she replied. "Being at the secure facility isn't a piece of cake, and since you and I never actually discussed it before you left us, I don't know what you expected. There are no kids there and the Diggles are often away on assignment. The options for William to have the kind of fun most kids have are limited."

Oliver nodded. "I get that. But you won't always be in protective custody."

"In theory, no. But at the moment, the FBI doesn't seem to be making a lot of progress finding Diaz. At some point you and I are going to have to figure what we do if they're never able to neutralize him - unless you've already made a decision about that, too." Her last sentence sounded a little bitter, so she did her best to lighten up. "And I can't believe I just used the word, neutralize. I hate that word."

Oliver shrugged. "They'll find Diaz."

I wish I were that sure, Felicity thought. Aloud, she said, "Well, I promise you the minute we're out of protective custody, I'll make sure William goes to one movie a week, stays out too late with his friends, watches too much TV, and gets at least one 'C' on his report card. It's probably going to be in English. Neither one of us likes Shakespeare."

Oliver smiled again – another genuine smile. His blue eyes were warm. "Good," he said. "Should we bring William back?" When she nodded, he looked toward the doorway and called, "William?"

William returned and sat next to Felicity. He glanced between his parents as if reading the emotional temperature and said dryly, "Did you sort everything out?" He turned to Felicity and added, "Was this a fundamental constant thing?"

Felicity laughed just as Oliver asked, "Fundamental constant?"

Before they could launch into an explanation, the bald prisoner at the other table was unshackled from the floor and his guard began shepherding him toward the doorway. As he passed Oliver's table, the prisoner paused and gaped at Felicity. "Is this the missus, Queen?"

Oliver didn't reply, but his face darkened slightly.

"My," Skull-Head continued, "she's a tasty little thing, isn't she? I think I might look her up when I get out of here. She'll probably be ready for a man by then, since you're going to be in here a long time, Queen."

Felicity tried to keep her eyes on Oliver and avoid looking at the prisoner. Oliver, on the other hand, stared at the man as if he was calmly thinking about ways to dismantle him. Skull-Head chuckled, undaunted.

His guard prodded him with a baton. "Let's go," he said sharply.

Skull-Head gave Oliver one more grin and then walked to the doorway. Jackson stepped aside to allow him to pass and then – suddenly – the prisoner doubled over and his bald head snapped up. His hands, still shacked together, went protectively to his nose. Felicity could see blood leaking through his fingers. She couldn't figure out what had happened, until Jackson glanced briefly at her with a satisfied expression and then returned his gaze to his shoes.

The whole thing had happened in less than a second. The prison guard didn't say a word.

Oliver raised an eyebrow at Felicity. "Well, he may not talk to you a lot, but I'm guessing your bodyguard is one of those guys who think actions speak louder than words."

Felicity studied her husband's expression. She couldn't tell if he was pleased or angry. "Is that a good thing?" she asked.

Oliver sighed. "I don't know. I guess it's a good thing. I'd be lying if I said I didn't want to do what he just did."

"Well, let's find a way to get your ass out of prison and then you can."

Oliver gave her a half-hearted smile. "Sounds like a plan," he replied. There was no conviction in his voice, but neither was there the dull resignation that she'd heard when she'd first come in. It was progress, she thought. Baby steps.

"Now, what's this thing about fundamental constants?" Oliver asked.

A/N 2: The first draft of this story was a lot harder on Oliver for his unilateral decision to turn himself in. I decided Felicity wouldn't kick him when he's down, so I eased up a little. Still, I really dislike what Oliver did. In particular, because:

1. Felicity, his wife, learns about his decision to surrender at the same time as the rest of team. Oliver found time to show John the Arrow suit and to do his "farewell tour" with the other team members. The adult thing would have been to tell his wife privately, before everyone else. (And I don't buy that Oliver was afraid he might lose his resolve or she might talk him out of it.)

2. This decision has huge ramifications for Felicity and the way she lives the rest of her life. As the audience, we know Oliver will probably find his way out of prison because the series is about The Arrow. But within the universe of the show, he's going to be in prison for decades, if not the rest of his life. So he's basically making Felicity a single parent and then leaving her.