The kid was so certain in his convictions, talking to Barry as if they'd know each other for years. Who ever had raised the boy knew an awful lot about The Flash's identity and done a damn good job in brainwashing the lad. "Right." He offered "So, Barry..?" There was no way he'd call the teenager Barry junior or, God forbid, BJ. "I know you think you're my grandso-..."
In the blink of an eye he was next to Bart, catching the boy's wrist as his curious poking of the machine grew progressively faster. "Let's just say it involves explosives and is allergic to prodding."
He motioned over to a chair. "Do you think you could sit down for a few seconds?" There was nothing threatening in Barry's body language. "Tell me everything from the beginning, including your Mom and Pop because," He sighed, there was no easy way to say this: "I don't have any children."