What does it feel like?

It's an energy system, renewable, self-replenishing, and once he reaches a certain speed it's easier to keep going than it is to stop. His jogging speed is around three hundred miles an hour; his runs usually take place in the six-seven hundred mile per hour range.

Beyond that – beyond that, he's pushing himself hard, forcing his body to go faster than even it thinks possible.

When he climbs above eight hundred miles an hour, he feels like he's cheating. Like it shouldn't be possible. It's the equivalent of saying jump and rocketing twenty feet into the air, exhilarating, mind-blowing in the best way. Like he can fly if he tries, commanding his body in a way most humans never get to experience – finding an upper limit beyond muscles and sinew, a limit only dictated by how fast he can go.

He has to trust his instincts and follow the past of least resistance when he tears through Central City – a crash at this speed would be catastrophic.

It should scare him, running so fast he could die if he tripped, but he's forged from iron and steel, his blood is molten, and his pounding heart is promising that he will come together and run again no matter what he hits. So he runs with abandon, without reservation, trusting his body, trusting his own speed.

Above nine hundred miles an hour, he becomes the annihilating force, the collision that could pulverize an object, and it elicits a whooping cry that gets lost in the oblivion, a surge of adrenaline rushing through him. It's so potent he thinks it could stop his heart if he didn't keep going, so he does, pushing faster and faster and faster, inching upward in ten-mile-per-hour increments.

The drag is incredible above 950 miles an hour, but Barry's body is so coiled, so powerful, that he meets the resistance with breathless ease, and suddenly it's becoming easier and easier and easier to just run until he's flying at 1,200 miles an hour.

It's a learning curve, a physiological phenomenon he can't explain: in the instant he feels like he's reached his max speed, he leaps and hits the grounding running, running faster than he ever has in his life, running fast enough that he can't see anything, can't feel anything but his heart beating hard in his chest, his breath tearing out in delighted, gasping sears.

It's him and the lightning, now.

The energy he generates is intoxicating, and he's sprinting but he can barely feel it, breathing deeply, steadily, wondering how fast and far and hard he could really push himself.

It's like no one else exists, like the world itself dissolves and then he's left on another plane, running faster than he should be, riding a wave of energy so strong he pushes past Mach 2 in a matter of seconds.

He thinks, I could run forever, and his body obeys, and it's beautiful, here, like he can transcend entire star systems without ever leaving earth, that same ethereal sensation overwhelming him as he embraces something too pure and joyful for words.

He feels like a kid in a wide open field when there aren't adults around and he can take off, and no one is there to watch him or criticize him or call him home, so he can just run, and run, and run, as fast as he can, embracing his own power and the way his heart pounds and his breath comes in gasps, because it's above him, it's the greatest tangible feeling he knows.

Surrounded by the field of energy, he feels safe, completely untouchable, and he laughs at the thought of the Reverse Flash trying to catch him now.

He's not fast enough to catch Zoom – not yet – and he wonders what it feels like to run that fast when he isn't running blind out of fear, pushing himself too fast, too quickly, when he can take his time, build up to it, until he can feel the pure, raw energy supplementing his own.

But Zoom doesn't matter, not when he can fly.

He cuts through the darkness and feels the utter solitude of his world, and it's comforting, like he's on another planet where there is nothing but the freedom to run.

He pushes himself hard. In that moment he thinks he even knows what it feels like to die: the detachment from everything, the fear, the ecstasy, being on the brink of something different.

He's a ghost, and there's a breathtaking lightness to his being that lets him go, releases him from the pain of exertion, the stress of a rocketing heart, and gives him slowing lungs, each breath coming at longer intervals than the next, until he's not even breathing, really, just inhaling energy and exhaling speed, his heart beat slowing to match.

In his mind's eye he sees Zoom, and he's moving but at a walk, a calm, measured movement that Barry can parry. Zoom lunges and he's free, outrunning, outlasting, and he can almost see exertion in the way Zoom's chest heaves as he gives chase because Barry knows that pain, too, when he's pushing too fast too hard too quickly, but he's safe, here, he's completely, utterly safe, and he's fast, he's too fast to see, not even a blur, just a pinpoint of existence tearing through the night, and he loses Zoom somewhere in the shadows of his imagination as he pushes farther and farther, interstellar.

He runs and runs and runs and thinks I could spend the rest of my life here.

It's better than the richest meal he's ever eaten, the best hug, the most satisfying laugh, a conglomeration of emotions that pours through his body instead of his mind, translating into more speed, more speed, more speed, and as he runs he feels all of them, simultaneously, in a way he never has before, like he's seeing colors for the first time, and he can't get enough of it.

He's out of control, but it doesn't scare him and he doesn't fight it. The energy is pure and raw and amazing, tangible ecstasy, and he's so drugged on it he can feel the stars in his veins and space in his lungs, pushing until he has no idea how fast he's moving, he's a blur to himself, he only knows that he's safe with the energy, and it's like it's alive, actively protecting him and encouraging him to keep going.

He runs and there's a span of one slow, elongated breath where he thinks I could die like this.

Then his suit crashes.

It's like every molecule of oxygen in his lungs evaporates, and he comes to a halt as fast as he dares, collapsing onto the pavement on all fours and wheezing hard, fracturing ribs with the force of his heaves as he coughs and coughs and coughs.

He's struggling to draw air into his lungs because it's a disarming sensation, like it doesn't belong to him, like he can't operate his lungs and his heart and his mind at the same time, but somewhere between the pain and the ecstasy his body gives a hard shudder and his heart starts beating again, hard, frantic.

He collapses onto his side, breathing in ragged gasps, eyes shut as he feels the energy pulsing through his system, healing him almost as quickly as he falls apart.

With painstaking slowness, he gets to his feet, gasping softly as pain lances across his chest, and he thinks, If I have a heart attack right now, I'm going to die.

He does the only thing he can think of: he runs.

. o .

It's the hardest thing he's ever done, bar none: getting up to speed again requires every ounce of agonizing will power he can give it.

But then he feels the energy surging through him, warm, protective, like a comforting god, and he feels the aches in his chest dissolving as his entire being fades into it, accepts the force around him.

The suit is choking him, and he's vaguely aware of the fact that he's going to kill himself like this, and he needs to stop, but he can't help it: the energy courses down his veins and he can't make a sound for how ecstatic it feels.

There's a universe inside him and the energy unlocks it, enables him to become so much greater than himself, to taste light and speed and energy for the first time, not through a glass barrier but up close and personal, in his blood, in his lungs.

And it tells him let go.

He feels a moment's hesitation, some deep, animal instinct rearing its head in protest, and then he folds.

It's like he doesn't exist anymore, like he's part of the speed and the speed is him, a single entity, powerful, unstoppable, and he feels like a paradox, an immovable object, an unstoppable force, meeting and breaking in the middle.

And the suit is nothing but he is nothing, too, and he should stop, he should, but if he stays here he can't feel anything but ecstasy, and it's like nothing else exists, nothing else matters.

Then the speed lets him go, and he tries to grab hold of it, feeling a profound sense of loss as he comes back to earth. He can't, and it's gone, and he's slowing, slowing, slowing, coming to a halt and sinking to his knees, his grief so potent his face is streaked with tears as he shakes and clenches his hands, trying to ground himself.

He sees himself holding his mother's hand as she dies, his father staring at him in anguish and joy from behind a prison window, and Zoom's face as he says simply, Goodbye, Flash.

Then he resolves into being, his blurred self coming into visibility, and he's on the floor in the middle of Star Labs, and Cisco is playing ping-pong with Jay, and the ball ricochets clean off the table when he comes into view.

"Dude," Cisco says, holding his chest. "Holy shit. A little warning."

Jay's staring at him, and Barry can see something dark there, a reproach that's beyond parental.

"Everything okay?" Cisco asks, chewing on a red vine, and Barry can't speak, can't meet Jay's eyes.

"We need to have a talk," Jay says, and Barry lowers his head. "Cisco. Would you mind giving us a moment?"

Cisco, looking confused, grabs a bag of red vines, says, "Sure." Over his shoulder, he adds, "Play nice."

The second he's out of earshot, Jay has him up against a wall, and he's glaring at Barry so hard he thinks it could actually kill, not that his lungs don't already taste like death, and he can't move, the arm across his throat and shoulders inexorably strong, his feeble attempt to push it away not even making Jay twitch.

"Do you know what happens to someone when you give them too much serotonin?" Jay says, voice below a growl, subsonic. "What happens when you keep the on switch too long in the pleasure centers of the brain?" He presses Barry harder against the wall and says very seriously, "They die."

There are tears running down his cheeks, but he feels blank, like he's been burned and can't feel anything properly.

"What you're feeling right now," Jay says, and his voice loses some of its edge, "is withdrawal. It'll pass." Huffing in disgust, he adds, "You're not even subtle, kid. How long were you running? Your pupils are blown."

Barry has to think about it, shakes his head, can't remember.

Jay sighs, releasing his grip on him, and Barry almost sinks to the floor before Jay puts a strong arm under his shoulders and keeps him upright.

He half-drags, half-carries him over to a chair. Barry sinks into it, feeling like a child, shrinking under Jay's glare.

"It's called Speed Force," Jay continues, "and you need to remember that. It is a force of nature just as strong as the ones binding your atoms together. You generate Speed Force, and if you pour too much of yourself into it, you'll never be able to escape it."

Barry clears his throat, tries to speak, finds he can't.

"Speed is a gift, Barry," Jay says, staring right at him, "but you know how dangerous it can be on a physical level. Emotionally? It can destroy you. Because once you see what it's like to die, to live without pain or fear or obligation, without friends, without anything you do here, without your very being, speedsters can lose their minds over it."

Finally, Barry finds his voice. "You got sucked into it."

"I did. Felt like I was gonna have a heart attack when I came down," Jay admits.

Barry huffs, can't comment. He feels sick to his stomach, holding his head in his hands, trying to absorb the fact that he almost died – did die, in a way.

"You can run," Jay says, pulling a seat up in front of him and sitting down, "as fast as you want, Barry. But you have to remember that there's more to life than running. That your friends, and family, and everything you know and love, exist here. This is your world. The Speed Force is just a part of you. And when it tries to pull you in, you have to decide which one you can live without."

Jay gives his knee a shake, pulling him away from the storm of his own thoughts, insisting, "The Speed Force is part of you, Barry, but it's not everything you are. Don't let it be."

He waits but Barry can't respond, just nodding slowly, taking it in, realizing in a breathtaking moment of clarity that his power has the capacity to kill him, and he almost let it.

"You shouldn't be alone right now," Jay tells him, and it's nice, having someone who just knows what to say, who's been there, who gets that he's not crazy for wanting it. "I'm going to invite Cisco back in, and we're going to be right here, and you can either join us or sit there or smash everything apart, but whatever you do, don't you dare start running."

Barry nods again, and he feels Jay squeeze his knee again before he pushes himself to his feet, walking away and returning seconds later with Cisco's chatter in tow.

"So like, on Earth Two, how many Star Wars prequels are there?" Cisco asks. He chances a glance at Barry, starts – "Barry?" – before Jay interrupts him.

"Three," Jay interjects, and Barry hears the tiniest shift of a hand on fabric as Jay redirects him away from Barry, and he can see the head shake, the silent no.

To his credit, Cisco goes along with it, and the sharp crack of the ping pong ball on the table keeps him from sinking too deep, their voices blending in his mind as he looks up and watches them play in slow-motion.

He forces himself to take a deep breath before standing, deliberately slowing his world down, and Jay looks at him momentarily, assessing, while Cisco asks, "Y'okay, Bar?" as he sends the ball back in Jay's court.

"I'll play the winner," he says instead, because he's not up to that conversation, not up to explaining a sensation Cisco can't feel or understand, so he stands on the sidelines instead, watching them play at normal speed.

Jay kicks Cisco's ass, and Barry steps forward to assume Cisco's spot, but before he makes it three steps Cisco is there, hauling him into a tight hug. He has to close his eyes for a moment, and it hurts but Barry can't bring himself to say it, because there's a lump in his throat that has nothing to do with physical pain.

Barry releases him, and he can still feel the warmth of it as Cisco smiles at him, handing him the ping pong paddle and saying simply, "Go kick his ass."

There are definitely things worth dying for, Barry thinks, but there are so many more worth living for.

Jay serves, and Barry feels a jolt as the ping pong ball cracks off his paddle, launching back into Jay's court, and they're not speeding but the sheer tangibility of it startles him, the sensation of settling back into his own skin taking a while to come to terms with.

In the end he has a monster headache and Jay crushes him, but Barry feels okay, and he can feel the speed under his skin but it isn't urgent.

And he thinks, I can live like this.

It won't be the last time the Speed Force tries to draw him in, but it will be the last time it succeeds.