"It's not going to work."

Barry isn't expecting the voice – was certain everyone went home – and he slips, flying off the treadmill and crashing into the safety mat hard on one shoulder.

Hissing in discomfort, he sits up slowly, staring at Jay as he steps inside the training room, expression steely, difficult to read.

"What's not going to work?" he asks, already pushing himself to his feet and climbing gingerly back on the treadmill.

To his credit, Jay doesn't try to stop him. He isn't fast enough, and Barry knows using his abilities against Jay is a low blow, a cruel reminder of how alike and different they are. They're both the Flash and they've both fought Zoom – but neither of them survived the encounter unscathed. In his head, he looks at Jay and thinks, You're what I could have become if it wasn't for Cisco.

Except he would never have become Jay.

He simply would not have survived the encounter.

Oh, Zoom would take his speed from him. But he wouldn't let him live.

"How does Zoom do it?" Barry asks, unable to help himself.

Jay folds his arms, frowns thoughtfully. "Do what, exactly?"

Barry almost shakes his head and says, "Nothing, forget about it." He almost starts running again, and Jay almost walks away. They almost forget it ever happened.

Instead, Barry sits down on the edge of the treadmill and rakes his hands through his hair. "I felt something – it was like he tried to take my speed away from me."

Jay's eyebrows arch. "You never mentioned anything about him affecting your speed."

"I told Caitlin and Cisco it was the serum slowing me down," Barry says, closing his eyes, holding his head in his hands. He doesn't know why he's telling Jay – he shouldn't tell anyone – but he can't stop himself from saying it. "Which it was, but he – he stabbed me, I felt something, and I've only felt that way when a meta-human siphoned off my electricity."

Jay sits on the treadmill beside him, says nothing, and Barry can feel the silence. He's always faintly aware that he's projecting a soft echo of electricity, like a fire throwing off heat. It's invisible to most people, but occasionally it surfaces – like a spark, or a jolt if he generates too much static electricity – and when he runs, it's lightning.

Each speedster has a signature: Barry's is yellow: bright, light, stable; Eobard Thawne's was red: sharp, tense, menacing; and Zoom's is blue: cold, precise, lethal.

Being near a speedster for a long enough period of time is almost like reading minds: they have a preternatural ability to gauge what sort of personality lurks in the lightning, whether it's stable or unstable, dramatic or dim, calm or stormy.

Sitting beside Jay, very conscious of his own heat, Barry feels absolutely nothing from him. It's utterly silent, and it's strange to him, disconcerting: he can't read Jay at all.

"Think of it like a blood transfusion," Jay says at last, and Barry looks at him, takes in how he's aged decades in the past few weeks, centuries over the past two years. "All I have to do is access a vein to siphon your Speed Force into me." Humorlessly, he adds, "Of course, it's rare for one speedster to ever have such an upper hand; it's fast, but as soon as you break the contact it stops. Zoom's abilities truly are exceptional. His methods – while crude – are effective."

Barry lifts a hand unconsciously towards the wound, feeling the knife-life thrust of Zoom's claw deep into his chest.

"You're lucky," Jay tells him, and Barry doesn't need to look at him to know why, to understand what could have happened. "Had Cisco not shot Zoom when he did there is a very good chance you would have lost everything."

"Why did it come back?" Barry asks, feeling an unexpected surge of gratitude for the lightning in his veins, the heat in his chest, the reality he gets to live.

"It's the difference between life and death, Barry," Jay says simply. "No amount of help can revive a dead man, but there's hope for one who's still breathing. You tap into the Speed Force without realizing it whenever you run; it's the reason you're able to run as fast as you can. It's the energy. Zoom siphoning some of it weakened you, but as soon as you started to run again you could access the Speed Force again and come back up to your normal levels."

Barry feels something tight settle in his chest at the comparison. "You're not dead, Jay," he says softly.

Jay smiles humorlessly, shakes his head, looks up at the ceiling. Barry notices the sheen in his eyes but doesn't say anything. He remembers the devastation he felt after Farooq stole his speed: the panic, the confusion, the horror that his life would be cold and dark and still forever.

He can't imagine what Jay feels like, weeks into his new existence as a speed-less speedster.

"As good as, Barry," he finishes at last, clapping him on the knee before standing up. "You need to rest. Running on a treadmill until you collapse isn't going to help you beat Zoom. Using your resources wisely is."

Looking up at him, Barry meets his gaze. "How can I stop him if he can take everything away from me?"

"I worked alone," Jay says, and there's a hardness to his voice, a self-rebuke that seems to burn low and cold in his eyes as he stares at Barry, forces him to accept every word, to understand what could happen if he doesn't. "You have friends who are willing to help. Use them."

"I can't put them in danger." It's quiet, impulsive, and he thinks it's the reason why he's here at all, building up his strength in the dark instead of working with them during the day. He remembers what it felt like to have his spine broken in half. He can't imagine putting anyone through that: letting Zoom tear them apart, break them, kill them.

Jay actually smiles a little, sad, amused. "Everyone is in danger, Barry. As long as Zoom still has access to your world and mine, everyone is in danger. Your friends want to help. Let them." There's a moment when his expression softens, like he's remembering something, and Barry wants to ask but doesn't pry, lets him walk away, pausing near the door. "Zoom won on Earth-2," he admits, face too shadowed to read. "He scared everyone into submission. My friends did the only thing they could to survive: fled. Yours saved your life. Remember that."

And then he's gone.

Barry can still hear his footsteps, neat, quiet, as they retreat, until the door slides shut and it's silent again.

Reaching up to thread his fingers behind his neck, he stares at the ground, thinking about all of the times when he had no choice, when he was the only one who could save them: like the Clyde Mardon's tornado, or the Mist, or even Multiplex. He has to fight alone. They can't help him. Zoom has to be the same – he's the most powerful enemy they've ever fought. Only a speedster stands a chance against him.

Except – Cisco took the shot at Zoom. Caitlin helped devise the serum.

And both of them kept him alive when he should have died in the wake of the attack.

He was never alone. They were there, coaching him, directing him, helping him as much as they could. They armed him, watched his back, devised ways to overcome incredible obstacles. Even when he ran after Tony solo, they found him and dragged him out from under the debris; even when other meta-humans overwhelmed him, they were right there to intervene, even defibrillating him in the field; and when Zoom attacked, they were there.

It's not all about speed, he thinks. There's a weakness to Zoom's approach, and they'll find it, and exploit it, and take him down.

And, Barry thinks, as he drops his hands and climbs to his feet, turning off the lights behind him as he leaves, maybe they'll even find a way to restore Jay's speed.

You're not a dead man.

That night, he dreams of two red speedsters chasing down Zoom, yellow and orange lightning blurring in their wake. He watches in slow motion as Zoom turns around, running towards them, and Barry knows what to do: he diverges, coming around his left side as the red speedster meets Zoom head-on, and before they can collide Barry throws a lance of lightning straight into the fray, catapulting Zoom back with a deafening crack.

It's not over – and Barry doesn't know if they're strong enough, feels breathless with adrenaline as he rushes towards them – but as Jay launches a pursuit and Barry follows, he feels a grin of satisfaction at the thought that he finally gets a chance to fight like hell.

And in Jay's lightning, he sees it: verve, solidarity, determination.

Together, he thinks.

Together they can beat Zoom.

(And together, they can get Jay's speed back.)