Author's Notes: Fair warning, there is some dark stuff in here, including references to drug abuse, psychological abuse, minor character suicide, and major character death (doppelgangers).

Day 1.

Eobard: "Where am I?"

Barry: "Somewhere you'll never hurt anyone again."

"…Quite the turn, Golden Boy. You never struck me as the dungeon type."

"I made an exception."

"So it would seem. How long are you going to keep me here?"

"Like I said.

"You'll never hurt anyone again."

. o .

Day 2.

Barry: "I can still feel it."

Eobard: "Feel what?"

"Your Speed Force. It's … cold."

"It's hungry."

"You're projecting."

"Am I?"

. o .

Day 3.

Eobard: "FFI."

Barry: "What's that?"

"'Fatal Familial Insomnia.' A rare but potent genetic disorder that causes progressively worsening insomnia until the person dies. Also an affliction commonly associated with speedsters. In my time we call it FSI."

"…Go to hell."

"Irritability is one of the symptoms."

. o .

Day 4.

Barry: "I'm tired of seeing your face."

Eobard: "Yet you see it every day. You know, you've achieved the truly improbable: a literal hell out of heaven. Must be fun, isn't it? Watching your enemy, day-after-day, forced into proximity but utterly helpless to destroy them. Because you still need them."

"Why do I need you?"

"Because you're noble. Murder isn't one of your conditions."

"I've killed before."

"Ever put a gun to someone's head and pull the trigger? Snap their neck? Crush their heart in the palm of your hand? You've killed, but you – and I mean specifically you, not future you; he's a menace in some timelines, the kind of Flash I would fear – you can't kill me. It's too personal. It's too intimate. It has to be faceless or in a rush of thoughtlessness, or else you see your enemy's face and realize he's human."

"I'm sick of listening to you rhapsodize."

"Yet you listen to me every day."

. o .

Day 5.

Eobard: "Here I thought you'd forgotten about me."

Barry: "If only."

"That for me?"

"Could be. If you answer a question."

"Withholding food. That's very heroic."

"Why did you kill my mother?"

"I didn't, actually. You stopped me."

"You were going to."

"And you were going to let it happen, Barry. You saved yourself. Not her. Not your father. I could just as easily have killed him."

"This is your fault, not mine."

"How exactly are you so sure?"

. o .

Day 6.

Barry: "What's the cure?"

Eobard: "For what?"

"FSI."

"Oh, that's easy. Die."

. o .

Day 7.

Eobard: "Happy one-week anniversary, Barry. Feels terrific to be on the other side of the glass wall, doesn't it?"

Barry: "You know, one of your doppelgangers, the evil Wells I knew? He spent fifteen years keeping an eye on me. Fifteen years watching."

"That must have been incurably boring."

. o .

Day 8.

Barry: "What do you want?"

Eobard: "My freedom, my home, your Speed. Something tells me you're not giving me any of those things."

"Consider me negotiable."

"Why the change of heart?"

"I can't – sleep."

"You think I have a solution."

"You know about FSI."

"Yes. And it's terminal."

"You're still alive."

"I don't have it. I found it in your archives. Thawne blood is purer than the Garrick line. You inherited the disease from your maternal grandfather. Your nickname was almost 'Bart,' but you're saving that for the future—"

"Don't talk to me about the future."

"If you think you haven't already irreparably damaged the timeline, you're deeply mistaken, Flash."

"Nothing is irreparable."

"This is."

. o .

Day 9.

Eobard: "Your future self would have killed me by now. Your hopeless magnanimity knows no bounds. What are you hoping to gain?"

Barry: "Freedom from you. From what you've done to me and my life."

"You're failing on both accounts."

"I know."

"So why don't you kill me?"

"I don't know."

. o .

Day 12.

Barry: "Dinner."

Eobard: "About fucking time."

"You know, human beings can survive up to three weeks without food."

"And at least nineteen days without sleep."

. o .

Day 13.

Eobard: "So do you have a will written up about what you're going to do with your pet Eobard once you're gone?"

Barry: "Just be glad I came back."

. o .

Day 14.

Barry: "I'm not healing as fast."

Eobard: "Side effect."

"Of FSI?"

"Of stress."

. o .

Day 16.

Eobard: "There's a formula."

Barry: "For what?"

"Speedster-strength painkillers."

"…You're withholding it."

"Only if you're unwilling to bargain."

. o .

Day 18.

Barry: "I'm willing to negotiate."

Eobard: "I can see your cheekbone. I don't mean the skin."

"One favor."

"Black Flash?"

"One."

"…Big Belly Burger."

. o .

Day 19.

Eobard: "Only twenty-four hours left."

Barry: "Until what?"

"You set the world record for most consecutive days without sleep."

"How do you know I haven't broken my streak?"

"You forgot to lock the cage again."

"…Why are you still—"

"The door jammed when I tried to open it from the inside."

"Well-rested me was smart."

"Well-rested you hasn't existed since before the particle accelerator explosion. When was that, by the way? Clearly it was on an accelerated timeline here. You're the second youngest Flash I've ever met."

"Second youngest?"

"Particle accelerator."

"2014. Second?"

"I met your twenty-four-year-old doppelganger. It was a shame to kill him. Didn't change a damn thing. It's amazing, Flash: on the one hand, you are truly immortal, because no matter how many doppelgangers I kill, you persist."

"How many of my doppelgangers have you killed?"

"Seven."

. o .

Day 22.

Barry: "Tell me a story."

Eobard: "Why?"

"I'll get you Thai food."

"What kind of story?"

"About the seven."

"Why do you want to know how you died?"

"I don't. But it could be useful."

"Fine. I broke one's neck, I drowned two, I suffocated three, I stabbed four, I shredded five's heart, I electrocuted six, and I annihilated seven. I want every dish on the menu."

. o .

Day 23, later.

Eobard: "See, Barry? This isn't so bad. Giving in. Letting me win. Imagine how liberating it'll feel once you let me out."

Barry: "'Once.'"

"You will. And then you'll die when I break your pelvis and you bleed out internally."

. o .

Day 27.

Barry: "You're psychopathic."

Eobard: "In my time, none of you exist. I hardly consider it psychopathy to kill people who are already dead."

"But see, I'm not dead. And neither is Cisco or Caitlin or Iris or Joe. We're all still alive. Right here. Right now."

"Barry, if you think I'm going to apologize for killing them, I'm not."

"I don't want an apology."

"Then why'd you bring it up?"

"Because I can't stand the fact that you can still sleep at night."

. o .

Day 30.

Eobard: "Our one-month anniversary. I'm impressed. You're starting to look pretty withered, though."

Barry: "Fuck off."

"Irritability is one of the symptoms."

"Maybe I'll take it out on you. Take you down with me."

"Don't posture."

"You've killed me seven times. But you mentioned a future Flash you fear. How many times have I killed you, Thawne? You think I'm incapable – but I've already done it."

"If you want to know the answer to that, you'll have to ask one of those future Flashes."

. o .

Day 31.

Barry: "I feel sick."

Eobard: "More Thai for me."

"Twenty-nine. Twenty-nine—"

"Who's the villain now, Flash?"

. o .

Day 35.

Eobard: "I'm faster than you are."

Barry: "I … am aware."

"I don't mean physically, although that's also true. But when I kill you. I'm quicker. You just love to draw it out, don't you? People fear you more than me, when we're contemporaries, in my time. Because they know I'll move on. You want to send a message."

"What kind of message?"

"'There's only room in this world for one prime.'"

. o .

Day 36.

Barry: "You mentioned 'prime' – what does that mean?"

Eobard: "It means you're the only cancer patient whose chemo isn't killing him."

. o .

Day 39.

Eobard: "You know, you can overdose on speedster-strength painkillers."

Barry: "I don't care."

"You'll just leave me to rot, then?"

"I don't care."

"Apathy is one of the symptoms."

"Of FSI?"

"Of overdose. Lay off."

. o .

Day 42.

Barry: "I'm happy here."

Eobard: "Are you telling me or the universe?"

"I'm happy here."

"Because it's working on neither account."

. o .

Day 44.

Eobard: "Bar."

Barry: "Don't call me that."

"This is an intervention."

"How can you intervene? You're in a glass box."

"Don and Dawn."

"What?"

"They're your kids. You want to see them someday, don't you?"

"… I –"

"Go throw up, drink a fuckton of water, and lay off the painkillers. Got it?"

"Why are you—"

"You're still useful to me."

"You mean, I still have the key to your unlockable glass box."

"Precisely."

. o .

Day 47.

Barry: "It's weird."

Eobard: "What's weird?"

"Not having my team."

"Lone wolves fight with fewer pack members."

"Lone wolves have no pack members."

. o .

Day 50.

Eobard: "Another beautiful day in our brave new world. Cell walls. Rain. Just sings to you, doesn't it?"

Barry: "Thawne, I am tired enough to kill you, don't push it."

"You brought me food. And now I get to have my entertainment from the fool."

"I can still eat this. By myself."

"Yeah, but that nausea's been weighing you down for a few weeks, hasn't it? You're losing weight. How haven't your parents noticed?"

"Apparently it's closer to the lanky, pre-Flash me they're used to, anyway."

"Ah. He was happier, you know. That bolt from the blue just brought you misery. And pain. And a lifetime of agony."

"Which I can now mitigate."

"You mean abuse. This is why I never tell your younger selves anything – you're morons. It takes fifty years for any lesson to sink in with you. At least your future selves have a fighting chance. They're more fun. It's just child abuse at this level."

"Yet you persist."

"I've crushed your heart in my hand. You're dead to me. It's not abuse if you don't exist, and legally, you're an adult."

"What about when I was eleven and you spied on me? Twelve? Thirteen?"

"I never spied on you. I have no recrimination for the actions of my less-brilliant doppelgangers."

"You're a psychopath."

"You think you aren't?"

. o .

Day 52.

Barry: "You were wrong."

Eobard: "About what?"

"FSI. I slept. Fell asleep. For the first time in two months."

"Congratulations. Your next lapse will last four years."

"…Fuck you."

. o .

Day 56.

Eobard: "You can't trigger the recoveries."

Barry: "I'm a scientist. I don't accept that."

"Very well. Expend your precious energy on a problem we haven't solved in two hundred years. You're a marked man. Every Barry Allen manifests FSI, but only the speedsters have the vulnerability to it. You should be grateful I kill you. It's much less painful than dementia."

"Stabbing me is less painful?"

"Losing everyone you love, that mind of yours, your ability to control the Speed Force? Yes. Stabbing is far kinder. I euthanize you. You're welcome."

"You're sick."

"I'm not. You are. Gotta love how the universe balances out."

. o .

Day 61.

Barry: "Happy two-month anniversary."

Eobard: "You're in a good mood."

"Got to celebrate my mom's birthday."

"That's sweet. My mother died when she was forty-seven."

"You want me to say I'm sorry?"

"You are."

"You killed my mom."

"You just celebrated her birthday. There's a flaw in your argument, Barry."

"What was her name?"

"Elle. Old name."

"Elle. Your father?"

"Xavier. Forty-two."

"They'd be so disappointed in you."

"You speak from a place of such confidence for someone who has a man locked up in a warehouse indefinitely. You'd be such a wanted man if the public knew, Flash."

"Guess you shouldn't have gone back to this universe where no one knew you existed."

"And how many times have you changed the timeline? This isn't your first."

"You can ruminate on that. I'm going to go spend time with my living family now."

"It won't last."

"Keep pushing it and neither will you."

. o .

Day 64.

Eobard: "Ten-dollar word, Barry. 'Hubris.' Means excessive pride. Hauteur."

Barry: "Yes, I am aware of what the word means."

"Self-importance. Egotism. Haughtiness."

"I could leave you here. Walk out for good."

"Arrogance."

"Fuck off, Thawne."

"Conceit."

. o .

Day 68.

Barry: "I'm happy."

Eobard: "I don't think you know what that word means."

"I'm happy."

"You'll never be truly happy, Barry."

. o .

Day 71.

Eobard: "Do you ever tire of being a Golden Boy?"

Barry: "People still need to be saved."

"That's not an answer."

"Yes. I do. And people still need to be saved."

. o .

Day 76.

Barry: "A proposition."

Eobard: "For what? My freedom?"

"Ice cream."

"I'm listening."

"Tell me what they were like."

"Who?"

"Your parents. Elle, Xavier. I want to know."

"You want to know why I became a monster."

"I know why. You're selfish. You wanted more. You destroyed everything to get what you wanted."

"You really think so highly of yourself, don't you? 'Everything,' Barry? You're one tiny part of it. An exchangeable, erasable component."

"Your parents – they died suddenly, didn't they?"

"Xavier took his own life four days after Elle died of cancer."

"…That's – heavy, Thawne."

"I was fourteen. I got over it."

. o .

Day 78.

Eobard: "You don't ever really get over the deaths of your parents."

Barry: "No?"

"You of all people know that."

"Doesn't mean I went on a warpath to – what, redeem them? Mine were murdered. However tragically, yours died of natural causes."

"Their deaths aren't the reason I became the Reverse Flash."

"Why did you become the Reverse Flash?"

"What are you willing to bargain to find out?"

. o .

Day 79.

Barry: "If you could undo it all, would you?"

Eobard: "No. Would you?"

Barry: "In a heartbeat."

. o .

Day 81.

Eobard: "How long are you going to pretend you can keep this up?"

Barry: "As long as I have to."

"For the rest of your life?"

"If I have to."

"That's just it, Bar. You don't have to. You could let me go."

"So you could, what, finish what you started?"

"You're breaking the timeline more irreparably than I ever have. How have the time wraiths not come after you?"

"They did. Before."

"It's bad news when the Speed Force thinks your own actions are greater punishment than whatever it might deliver."

"Good night, Thawne."

. o .

Day 82.

Barry: "We could have been friends."

Eobard: "You don't believe that."

"I don't. But it's a nice thought."

. o .

Day 83.

Eobard: "Xavier loved the piano. He thought I'd make a good pianist. Elle was very powerful, one of the movers-and-shakers. Her death destroyed him."

Barry: "Why are you telling me this now?"

"Your time's running out. You can feel my Speed Force?"

"Barely."

"I can feel yours. It's feverish. Overheating. You're burning out, Flash. I give it a week."

"And then what?"

"Speed-death."

. o .

Day 84.

Barry: "You're lying."

Eobard: "What reason do I have to lie?"

. o .

Day 85.

Eobard: "That's one hell of a flesh wound."

Barry: "Do you want this or not?"

"Food, yes. Shark bite?"

"Mm."

"You need to replace the bandage. It's soaked through."

"I can feel it, Thawne."

"You wanna lose an arm?"

"Of course I don't want to lose an arm. Why the hell do you care?"

"I don't, really. I just find the smell of putrefying flesh rather unappetizing."

"You know what? Maybe a little hunger will be good for you."

. o .

Day 87.

Barry: "We've been here almost three months."

Eobard: "I was quick. You were always slow."

"What's that supposed to mean?"

"It means you love to play with your food. You're a goddamn sadist."

. o .

Day 88.

Eobard: "You don't like the truth, do you?"

Barry: "That I won?"

"That you'll never win. Because this isn't your game. Well. Not yet. To him, I suppose – future you, that is – this is right up your alley."

"Would you do me a favor and shut up?"

. o .

Day 92.

Barry: "Dinner."

Eobard: "There better be curly fries."

. o .

Day 94.

Eobard: "How badly do you want to die, Barry?"

Barry: "I'm not going to let you go."

"You're such a fool. And all I have to do is wait until you have bled yourself dry, and then we can both rot together. How lovely. It won't stop, you know."

"What won't?"

"This. The contention. The vying. We're destined to fight. Know what two opposite charges do?"

"Repulse."

"On the same plane, yes. But two opposite charges, brought into contact, will align. You and I are opposites. No matter how far you run, I'll never be far behind. And no matter what future I return to, some future Flash will be there to ensure I don't see it. It's a wonderful game."

"This is not a game."

"You were always so invested. Ever think about how much easier life would be if you didn't care so much?"

"Go to hell, Thawne."

"You're taking both of us there."

. o .

Day 95.

Barry: "I need you to kill my mother."

Eobard: "With pleasure."