History:

Impulse, or 'Bart Allen', as the kids at school call him, is one of the most interesting guys I've ever met. Seriously.
He's smart, funny, from the 30th century, cute... Oh, don't make that face at me. Like you didn't see that coming....

You see, Bart is the grandson of Barry Allen, the Flash. He inherited his grandfather's super-speed powers. At first this was a problem. He was aging at superspeed as well. The government kept him in VR simulations to keep him stable, but did nothing to slow the aging. Finally his grandmother, Iris Allen, took matters into her own hands and brought Bart to the present. She hoped that her nephew Wally West, the current Flash, could help him. Eventually he did, and Bart hung around long enough to get sucked into the Terminal Velocity storyline.
Afterward, Wally was totally sick of Bart, so he got sent to live with Max Mercury, a semi-retired speedster, down south. (Manchester, Alabama) You wouldn't believe how many super-villains can show up in a small southern town. Not to mention non-super villains, semi-heroines with stage mothers, girlfriends smart enough to figure out a secret id, and really annoying school personnel.

In 2980, Bart Allen was born to Don Allen and Meloni Thawne, daughter of president Thawne.  After the death of his father at the hands of the Dominators, Bart Allen was abducted by the alien race for study. Eathgov forces located and rescued the subject, and placed him immediately into Eathgov labs, officially beginning this project. For security reasons, Meloni Thawne was told that her son had been killed in the raid, and was to remain under this belief unless decided otherwise by the head of the project, President Thawne.

Bart inherited his grandfather's (Barry Allen) super speed and utilized it since birth making him the only speedster ever born with super speed.  However, Bart's super speed affected his metabolism and accelerated his aging.  By the time he was 1 he looked 2, by the time he was 2, he looked twelve, blah blah blah.

Earthgov police took Bart into their care, and told Meloni that he had died.  They plugged him into a virtual reality void that taught him at the same rate of his growth, but it was like living in a big video game.  It gave him a sense of fearlessness and impulsive thinking, thus making him true to his name.  But when Bart's grandmother Iris finds out that that earthgov had different plans for bart (bad ones), she decides to bust him out and head for the 20th century via the time stream.  Now in the 20th, the Flash helped him put his metabolism back in check and Bart (now Impulse) helped him defeat Cobra.

He is a member of Young Justice., and  now lives in Manchester under the strict arm of his mentor, Max Mercury. Bart lives in a small, slow Southern town. He belives this is a punishment. He is correct.