Everything must be shared, including Speed.
Speedsters don't particularly care to share Speed. It's a fact of nature. In the multiverse, there's only so much of it to go around. A speedster with it implies a speedster without. Supersymmetry: where one exists, an opposite must be somewhere.
There is one exception. Because he lives at peak capacity, Barry has nothing empirically to gain from relationships with other speedsters, only something to lose. It's a cynical way of scrutinizing potential allies, but the trusting route got Eddie and Ronnie killed and destroyed a lot of Central City. He can't afford to let people into his life who take what he is all too willing to give. Not if he wants to live long.
One thing Eobard gave him: distrust. Barry walks in skeptical of Jay Garrick, a man who shares not only a desire for his team but also shares with him the burden of another world. He knows about Zoom, but Zoom isn't his problem – not unless he wants Zoom to be. He could walk away; he has no obligation to rescue every Earth.
He also has no obligation to save every stranger he encounters, Barry reminds himself grimly, standing outside of the particle accelerator door. Selective altruism is a moral minefield, and missteps can prove fatal. If he opens the door and Jay kills him, then he'll know whether his next step was correct, but he can't know until he takes it. He must risk everything to gain something.
That's what it means to be The Flash.
He dials in the door unlock code and steps back. Jay looks up when he walks into the room, and the mixture of hope and relief in his expression twists Barry's stomach. For a moment, he can almost see – with a painful degree of clarity – another Earth, where—
"Why should we trust you?" a deep, mechanical voice intones.Barry can't see the speaker; the darkness is absolute. "Your purported threats have never even been hinted at here."
Barry presses his hands flat against the glass of the particle accelerator cage door. "You are in great danger," he says.There's urgency under his skin – how long until The Plague spreads?Does he carry it, even now, onto their Earth?He was certain the decontamination process was complete, that Speed Force would burn every trace from him, but if he is wrong— he is the very monster they have every right to fear. "You have to believe me."It's hard to plead his case before a robot, but he knows there are humans behind the tin and darkness and cloying fear in his chest.They'll listen.If he pleads the right case, they'll understand.
But the longer he speaks, the shorter the robot's responses become.Finally, it goes monosyllabic, yes-no answers, overwhelmingly, unbrokenly 'no.'His hands twitch in agitation.His stomach hurts with how hungry he is, his nerves driving him insane in the dark and cold quiet.A hiss of hydraulic air pumps cold into the cell, and he vibrates in place to keep from freezing solid.
"Please," he insists. "I don't want your world to succumb to the same damnation as mine.But terrible things are coming, and you have to listen to me, and make a cure, or you'll never survive."
"Populations can rebound from a handful of genetically unique individuals," the robot replies, unexpectedly verbose. "Even if your apocalypse unfolds, the human race will prevail."
Barry shivers, only partially attributable to the cold. "You still have time," he gasps. "You're still outside its radius.It'll keep spreading until it consumes the multiverse.You can stop it here."
The robot hums, and the cold intensifies.His shivers slow to stillness, skin bluing in the dark.
"Wh-what are y-you d-doing?" he asks them.
"Decontamination," the robot replies. "We would have to boil you to remove any traces of your … plague.That would kill you.This is superior."
"C-c-c-cold is leth-lethal t-t-t-too."
"Are you familiar with cryogenics?"Another blast of cold, so intense it burns.Barry yells and barely hears what they say next. "You should be fine.If not, well – you'll make an interesting specimen.We've never frozen a speedster before."
Barry opens his mouth to argue, but his jaw will not budge, and when the cold intensifies yet again his breath freezes in his chest and his heart … beat … stops—
"Flash?"
Barry jerks, looking around in bewilderment. They let him out? Why did they – and it's warm, it's warm, lightning humming affectionately under his skin, he's alive, he's alive—
He shivers once and abandons the memory, trying to banish the sense of doom from his thoughts.
"Speed Force," Jay says, half-fond, half-rueful. "Can be a, uh. Powerful enforcer. What did you see?"
Barry looks at him, resisting the urge to share it. "We need your help," he says instead. "Stopping this … Sand Demon."
Jay brightens and nods. He seems neither resigned nor relieved, simply ready. "I have an idea."
. o .
Jay proves his worth. In the field, even Speed-less, he's an indispensable ally in a fight.
Barry has no way of truly knowing if he's a speedster, but he does know that Jay risked his own life to help him stop something he didn't have to.
Because that's what The Flash does.
. o .
In six months, he will have the counterargument.
The unguarded den is a target for the stranger.
"I come in peace," the man says, and the inhabitants listen, even though Stranger Danger sits deep in their bones.
He tells them a good story, and they listen, and they learn, and they start to think he cannot harm them because he is part of their pack.
Then the stranger slips away and removes his sheep's clothing, a wolf unmasked, and breaks the back of one of its adoptive family members.
"I warned you," the man says, referring to himself and another.
Still they trust, because it is easier to believe a half-truth than an impossible lie, that he is on their side than he can possibly be against them, but the truth will not die.
The wolf pulls off its most impressive feat when it destroys itself.
The pack mourns, and misses, and wants for their adoptive kin, but they don't know that the wolf is still there.
When the wolf pulls off his disguise in plain view, they know that they have been deceived, but it is too late.
Everything must be shared, including consequences.
. o .
Sitting alone on his pack's porch, Barry dares to wonder what might have changed, had he simply given "Jay" his Speed.
Had he shared unconditionally, wholeheartedly; had he let Eobard Thawne return to the future; had he behaved absolutely altruistically, instead of holding back.
If he died for them, would it have been enough to save his dad? Eddie, Ronnie? His mom? One version of him had already died: a time remnant in the magnetar's fury, a version of himself less than a billionth of a second younger. He was a willing sacrifice because both of them were thinking it, I have to die, even though only one was destined to.
Barry is selfishly grateful that it wasn't him.
Give everything you have, the universe insinuates, or nothing at all.But do nothing halfway.
He thinks, I don't want to be a hero if this is what it means to be a hero.
He changes the world.
. o .
And when the world changes him, and he sees what true loss is – what everything he has – entails – he rebels.
He lets one tragedy happen to avert another.
Mistakes and all, some universes are worth fighting for.