Bart Allen showed up out of nowhere one day, claiming to be related to Barry Allen.
Impulse, meanwhile, cropped up as a hero one day, and claimed to be related to The Flash.
These facts are obviously totally not connected at all.
The Reckless Youth
Pacific Standard Time
Blur, "Song 2"; The Clark Family Experience, "Standin' Still"
"Sorry, BB. Never was the best history student. Besides, we can't risk altering the time stream."
Classic, Heroic, Comedic, and Social
Gritty, Romantic, and Angsty
Bart Allen was born about one thousand years in the future -- or specifically, one possible future. In this reality, Barry and Iris Allen had traveled there from the past and had a family. Their children were Don and Dawn Allen, the Tornado Twins. The Allens were at odds with the powerful and ruthless Thawne family, however, even this feud could not stop Don Allen and Meloni Thawne from meeting and falling in love. They had a romance as true and as doomed as any ever before it, but they also had a child.
Their son, Bart, was born using the energy of the Speed Force at near-full capacity but with no control at all. He had inherited a mega-metabolic metagene from his mother, causing his body to grow at high speed. By the time he was two, he looked like a twelve-year-old boy. The only real way to stop this was to hook up to a special regulatory machine, which prevented him from physically moving to any notable degree.
To keep him busy, he was hooked into a virtual reality world of fantasy, where he lived his own zany little life. He was stopped at the virtual age of fourteen years old and the physical (effectively "actual") age of sixteen years old, while he was at the chronological age of eight. His only friend during this time was a computer program named Dox, left to care for Bart by Iris.
In the end, Bart's grandmother, Iris, devised a way to send him back in time to both save him from the dangerous Thawnes and to teach him to control his powers. She used Barry's time machine, the one which had carried them to the future in the first place, to travel back in time, where Bart could meet the present-day Flash, learn to control his powers, and be safe from the dangerous Thawnes of his home timeline.
Power:Speed Force (9)
Limitations: Requires access to the Speed Force; most aspects of the ability require Bart to be able to move somewhat freely
Overview: Impulse is connected to the Speed Force, a field of energy that allows him to move and perform tasks at hypersonic speeds. He suffers none of the negative effects from friction or G-forces that would otherwise be generated by this movement, and he can move through a room at high speeds with no more damage to the area around him than a strong wind would have.
General Applications: Bart's Speed power can be used in place of his Agility, whether to strike or to dodge, and if he's able to build up momentum, it can be used in place of Strength to deal damage. When in motion, Bart's Speed also features like Toughness to allow him to resist damage, but that will fail if his momentum is interrupted.
Breaking Physics: Bart's speed allows him to literally defy physics, running across water, up the side of buildings, and even upside-down along ceilings due to his great velocity. He can also vibrate his molecules at superspeed, allowing him to literally "phase" through solid matter equal to his Speed in density. He can only maintain such control for a second or so at a time, but that is usually enough for him to accomplish what he needs to do. Building up enough speed in a tight circle can also create a powerful air funnel at up to bart's Speed rating in force minus 2 (7/NEWS STRENGTH), but they tend to dissipate quickly once he stops keeping them up.
Hyper-Metabolism: Bart's whole body is basically overclocked, thanks to the Speed Force. As a result, his body fights off infections, viruses, toxins, etc. so quickly that they have essentially no effect on him. He also heals at many times the speed of a normal human, but this only works while in a resting state (as opposed to true "regeneration" in battle).
Speed Cognition:Bart's speed may also be used in place of Intellect when it comes to learning things, representing his ability to absorb information very quickly. Unfortunately, he doesn't always do a good job of retaining what he learns. Finally, Bart's speed of thought allows him to use his Speed as a defense against anyone trying to read or control his mind. His thoughts are simply so fast that most telepaths cannot keep up with them. However, this is of no use against direct mental attacks.
Bart is the future-tense grandson of Barry Allen, and as such he has a certain measure of knowledge about the Flash and his family, as well as an absolute certainty that they will help him if he ever needs it.
Bart inherited a ring from his future-grandfather that allows the storage of his clothing or a costume. He doesn't understand how it works, but it's definitely bigger on the inside, and it came with the costume that he wears as Impulse.
It might be a quirk of the Speed Force or maybe tied to Bart's time-traveling history, but whatever it is, Bart remains untouched by temporal manipulation or other time-distortion effects. Even if the world's timeline were rewritten, Bart would remain unchanged with his memories intact.
Flaw:Acts on Impulse
Bart tends to leap before he even considers the notion of looking. His brain not only tends to go super-fast, but it doesn't tend to even consider stopping to ask for directions.
Flaw:Hyper and Unfocused
Bart has one of the most catastrophic cases of ADHD known to science. For him, the entire world moves in slow motion most of the time. He has learned to cope with it fairly well, but he still tends to be jittery and easily distracted even at the best of times.
Flaw:Not Taken Seriously
No matter what he does, Bart seems to be stuck in the role of the eternal little brother to his friends and family. He has accepted this role, even playing into it, but it tends to make people take him much less seriously than they might otherwise.