WARNING: The following article contains spoilers for The Flash #751, by Joshua Williamson, Christian Duce, Luis Guerrero, Hi-Fi and Steve Wands, on sale now.

Ever since his resurrection during Final Crisis, Barry Allen's mother, Nora, has played a major role in the Scarlet Speedster's life as her tragic murder has loomed heavily over him for decades. This prominence has carried over to both the DC Extended Universe and Arrowverse incarnations of the character, with Nora appearing in the latter as the personification of the Speed Force whenever Barry finds himself trapped within the extra-dimensional realm. However, Barry's tragic history has been a relatively recent development for the character, only a little over a decade old.

Up until his eventual death during Crisis on Infinite Earths, both of Barry's parents had been alive and well, having raised him in a nurturing household before watching him become a successful forensic scientist with the Central City Police and one of the DC Universe's most beloved superheroes as the Flash. Both parents watched Barry get married and were both alive before the Crisis swept across the DC Multiverse. This remained nominally unchanged by the Crisis and the subsequent Zero Hour and Infinite Crisis events, but it was changed following Blackest Night.

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By the end of Blackest Night, Eobard Thawne has been resurrected by the White Lantern and immediately runs back in the timeline to personally torment Barry, unseen, throughout his childhood. This culminates in the Reverse-Flash changing history by brutally murdering Nora Allen and framing her husband, Henry, for the crime, resulting in Henry's lifelong imprisonment and Barry being raised in a foster home. With the change, Barry is now motivated to join the Central City Police Department to spend his off time with the police's resources and search for evidence to exonerate his father—and it's this late-night research that leads Barry to be in the crime lab when lightning strikes him and some chemicals, transforming him into the Flash.

Even after Reverse-Flash confesses the truth, Barry is still haunted by Nora's death—the revelation that he experienced a happy childhood with her in another life is particularly painful. This leads Barry to attempt to rewrite his own history by preventing her murder, inadvertently setting off a chain of disruptions to the space-time continuum that lead to the Flashpoint reality and subsequent New 52 era before Doctor Manhattan's role is revealed in Doomsday Clock. These events are loosely adapted on The Flash television series, with both the comic book and Arrowverse speedsters accepting that Nora has to die at the Reverse-Flash's hands for their respective universes to live.

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With Nora's death and absence playing such a massive role in Barry's upbringing, it makes sense that the person the Speed Force would select as its personification to him would be the Flash's late mother. This trend has even carried over in the current comics, as an encounter against the cosmic villain Paradox has the Scarlet Speedster banished to an otherworldly location where he is greeted by a vision of Nora Allen.

Barry Allen had been one of the most prominent superheroes in the DCU without a tragic backstory—no parents' meeting untimely ends or entire worlds exploding—but this was changed by his greatest enemy. And with Nora Allen dead and his father paying the immediate consequences under false pretenses, this has effectively made the most important figure in Barry's life his mother, both in terms of his motivations and why he is present in the crime lab when he becomes the Flash in the first place.

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