Due to his time-traveling nature, The Flash has a unique family life in comics, and the same holds true for his wife Iris. However, this has lead to some notable changes in their relationships in The Flash TV show. One big change involves the couple's children, namely the fellow speedster Impulse. Impulse is a fellow speedster hero from DC Comics, but his relationship with Barry Allen in comics involves more of a generation gap than it does in the Arrowverse.
While Impulse is Barry's son in the show, Impulse is actually Barry Allen's grandson in comics, with Barry's comic book son being one of the often forgotten Tornado Twins. And the diminutive role that Barry's kids play in the comics speaks to just how irrelevant he had become in the years when he was dead.
RELATED: Before The Flash: How DC's Armageddon Reshaped the Future
The Flash and Impulse
Impulse shows up in the CW TV series when Barry travels to the future. There, he's Bart Allen, Barry's future son and brother of Nora, a.k.a. XS. Bart's introduction in the comics was much different, however, as was his relationship with Barry. Debuting in The Flash #91 and created by Mark Waid and Mike Wieringo, Bart was the grandson of Barry Allen who was born in the far-flung future. He was born with superspeed and a connection to the Speed Force, with his overclocked metabolism artificially aging his body.
When the educational virtual reality used to teach his still young mind was obviously not enough, Bart was sent back to the present day to be with Wally West. Wally challenged the boy to a race around the world, with the overuse of his speed finally normalizing his metabolism. Bart, who would take the name of Impulse instead of Kid Flash, became a sidekick of sorts to both Jay Garrick and Max Mercury.
He wouldn't meet his grandfather face to face until the storyline Infinite Crisis, where he met Barry through the Speed Force. Their full-on interaction wouldn't occur until The Flash: Rebirth, however, when the resurrected Bart came to grips with his also revived grandfather being the main Flash again.
The Tornado Twins
In comics, Bart's dad was Don Allen, Barry Allen's son and one of the Tornado Twins. The Tornado Twins were conceived in the future, which is where Iris' spirit was taken to right before her seeming death at the hands of Eobard Thawne. This time period was actually Iris' native time period, making the family history of the Flash especially confusing. Iris would remain in the future after Barry's death in Crisis, raising her children Don and Dawn in a very different set of circumstances.
The government had become known for exploiting metahumans, leading Iris to have her kids hide the diminished superspeed that they inherited from Barry. When Wally accidentally ended up in the future, however, and his actions inspired the duo two use their powers as the Tornado Twins. Don would marry Melodi Thawne, ironically a relative of Eobard, causing their family to be attacked by the time-traveling Reverse-Flash. Don and his sister would later sacrifice themselves to defeat the alien Dominators, but Bart ended up in the past, becoming a hero in his own right. The TV show does away with Don and Dawn, though it's possible that another connection between the Allens and the Thawnes could be introduced later.