Aberration

"Chasing down time criminals and fixing the parts of history they screwed up. Aberrations, the captain called them."

- Mick Rory

Aberrations, also known as temporal aberrations or historical aberrations, are massive alterations of the existing timelines, prompted by the efforts of time criminals, disrupting the flow of time with anachronistic weaponry, meta-human abilities and other factors that could change the course of events, slowly cementing and affecting a timeline's future. According to Rip Hunter, it would take some time for the consequences of an aberration, even one as cataclysmic as a Nazi nuclear bombing of New York City, to ripple throughout time; while those safe in a temporal zone would remain unaffected.

The unusually large aberrations would also generate time quakes, emitting shockwaves in the temporal zone. An aberration could happen due to a time pirate selling futuristic weaponry to denizens of the past, or a "time nemesis" willfully disrupting the timeline for one reason or another.

Overview
A historical aberration would not immediately substitute the reality of the future, allowing the protectors of timeline some leeway and additional attempts in preventing the aberration's effects. The aberrations were prompted by rogue time travelers, such as a time pirate, or a "time nemesis", as the Waverider's crew unknowingly described the Reverse-Flash. Some of the denizens of the future would notice the affects of an aberration, recognizing that the reality is not as it's supposed to be.

History
After the fall of the Time Masters, Rip Hunter's team, calling themselves "the Legends", decided to take it upon themselves to protect the timeline from devastation, locating temporal aberrations through Gideon and going on missions to ensure the events pass more or less as they originally did, minimizing the aberrations' effects on the timeline. The Legends tackled on a number of such aberrations, one of which was the appearance of blaster-wielding assassins in 17th century France, seeking to kill the royal family.

After the French aberration case, Rip Hunter and Gideon calculated a 96% likelihood of another aberration in Bhopal, 1912. However, before they could attend to it, the Waverider was shaken by a time quake, originating from a cataclysmic aberration in New York City, 1942. The aberration would have long-going consequences, such as an atomic bomb drop on New York, a prolonged World War II until the year 1947, with many more casualties, and historical sources telling of such a war appearing all the way to the future of 2016, while the denizens of 2016 would still recount historical events as they were originally learned, with some of them, like Nate Heywood noticing that something wrong is happening with reality itself.

The 1942 aberration, while going according to Adolf Hitler's plan, was fueled by the efforts of the near-immortal Damien Darhk and, on some level, his time-traveling meta-human partner Eobard Thawne. Darhk would provide the Nazi regime with uranium, while their plans also required the abduction of Albert Einstein and Mileva Marić-Einstein, the only people capable of creating the atomic bomb by 1942. After their two time-travel attempts, the Legends both forced Darhk into wasting his nuclear missile on the Waverider, instead of the original target, New York City, and prompted Albert Einstein to reveal his ex-wife's role in scientific research to the public, making the United States government to provide security from the Germans to both Einsteins, safeguarding them. Realizing the plan's failure, Darhk and Thawne double-crossed the Nazis, as the Reverse-Flash slaughtered the U-boat's crew before greeting his partner. On their side, the Legends mused on the possibility of a rogue time traveler, a "time nemesis", helping Damien Darhk and the Nazis blow up New York City for their own amusement.