Bartholomew "Bart" Allen II is the patriarch of the King-Jones-Allen family. He is a masked superhero who works under the name Inertia, and is a member of the Justice League of America. He co-owns the Frenzied Spork chain of bakeries with his wife, Cissie King-Jones-Allen, and lives on a farm outside of Keystone City, Kansas.
There's tons of information on Bart here. Bart's history begins to branch at his death at the hands of the Rogues. From there he spent several years dead (he thought he was in a coma). After he was revived through mysterious circumstances, he found that both his cousin Wally and his grandfather Barry had returned, so he left Keystone for New York City.
Bart no longer felt like a child, so he retook the name Impulse and begin to work as a costumed hero out of New York. He re-established connections with his old friends, and met new friends, specifically a group of mutants that were affiliated with the X-Men.
However, Bart didn't come back to life the same as he'd been before death. Overwhelmed by his return, the life he found himself in, and his relationships, Bart ran at top speed, disappearing into the Speed Force. All that was left of him - in the plains of Siberia - was his artificial knee.
While in the Speed Force, Bart began to lose his individuality in exchange for infinite awareness. But he felt a pull to return to his former life, and eventually was able to leave the Speed Force, reconstituting his physical body in the process. He came back more introspective and less impulsive, but also more impatient and with a mind that was constantly ahead of the people he knew.
Bart cast off the name Impulse and took the name Inertia, feeling it more suited the "new" Bart Allen. Inertia was the name his evil clone, Thaddeus Thawne had used, and Bart was determined to change the way people viewed it. He met with some resistance at first, especially from his friends who had known Thad was the cause of Bart's death, but over several years - first as the leader of Young Justice and then as a member of the Justice League - the name of Inertia became known as a hero's name.
After his return he began to date Cissie King-Jones. The two opened up the first Frenzied Spork bakery in Manhattan. They were engaged on July 4, 2009, and married in the summer of 2010.
Since Wally is still the Flash, Bart has no intention of taking up the Scarlet Speedster's mantle any time soon.
As a kid, Bart was known as an impulsive and hot-headed kind of guy. He mellowed with age, but he's still the member of the team willing to jump into danger in an instant. As an adult, he's not jumping because he's not thinking, he's jumping because his mind is a hundred steps ahead of everyone else, considering possibilities and eventualities.
Bart is the heart of his group of friends. He'll do anything in his power to make them happy, from making stupid jokes to sacrificing his own happiness, and that extends to his children as well. Bart feels like the proudest dad on the planet.
Easy-going and open-minded, Bart can make friends quickly. Occasionally he turns people off because they think of him as a know-it-all, but with age he's gotten better about hiding this aspect of his personality from strangers.
Bart's primary power is speed, along with abilities that are common to comics speedsters, such as creating whirlwinds, running on water and vibrating through matter. That last ability will result in 'molecular taffy' if Bart does not concentrate; he also possesses an aura that prevents air friction while running. Before being shot in the knee, he was faster than the current Flash had been at his age. Bart does possess some abilities that other speedsters do not have. He has the ability to produce "scouts," Speed Force avatars that he can send through the timestream, but has used it infrequently since the death of one avatar put him in a coma. After being forced to use it during the "World Without Young Justice" crossover event, he was able and willing to use them with ease, up until he became Kid Flash.
Bart is resistant to the alterations in the time stream. Bart has the ability to recall everything he had ever read, heard or watched (which includes speed-reading every book in the San Francisco Public Library).
After Infinite Crisis, Bart's connection to the Speed Force is more difficult to control because he now contains the Speed Force and, in essence, is the Speed Force. When he taps into the Speed Force, Bart appears to have electricity crackling around him, and the Speed Force inside him has become so lethal, that he initially wore the Flash suit while running in order to prevent it from killing him. After remembering his experiences on an alternate Earth during a fight with Griffin, he began to gain a measure of control over the Speed Force before it was released from his body just prior to his death.
Shortly after he returned from death, Bart physically entered into the Speed Force, becoming one with it. After a few days he returned, having rebuilt his body and healed his knee. He also had the newfound ability to project his conciousness anywhere the Speed Force touched, which he believed to be related to his initial avatar ability.
After his knee was healed, Bart became the fastest known Speedster (to date), able to run at just under the speed of light.
Bart has been married to Cissie King-Jones for eighteen years.
He is extremely close to Max Mercury, and views Max as a father figure.
Bart has also grown close to his cousin, Wally West.
His best friends are Kon-El and Tim Drake.
Bart can be found on Livejournal @ nokidflash.
Bart's PB is Josh Hartnett.