he who hesitates is toast

Tony's pretty sure his resting heart rate has been solidly in the red for about a week straight now, but it still kicks up another notch at Barnes's agreement. He nods, more curt than he means to, strained and worried. "Vision," he says, and Vision courteously shows Bucky to the chair and station where they'd worked on scans of his mind before.

"I will place the diodes, Bucky," Vision tells him, and shows him the small round pieces of metal. Tony had tried to make sure they were as unlike the crown he'd described as possible, but he still needs something that's touching the man's skull.

"Okay," he says, and pulls up his schematics. "FRIDAY, start running the counter-program and begin recording. I want real-time updates accurate to the picosecond."

"You got it, boss," the AI answers, and an image of Barnes's mind unspools into the air before him.

Tony shakes out his fingers. "Sergeant, you're going to feel a little tingly – that's okay. If you start getting a headache, that's not. Just tell me if your head starts feeling tight or painful and we'll shut it off. Okay? Vision, okay?"