Warning: The following contains SPOILERS for The Flash season 6, episode 7, "The Last Temptation of Barry Allen, Part 1."
The latest episode of The Flash hints gives Barry Allen a new lightning color and costume, suggesting he has undergone a monstrous transformation into Negative Flash, the dark version of himself taken straight from his DC Comics' series.
The action of The Flash season 6, episode 7, "The Last Temptation of Barry Allen, Part 1," focused upon The Flash as he fought a battle for control of his body and soul. Infected by the villainous Dr. Ramsey Rosso (aka Bloodwork), Barry began hallucinating various nightmarish scenarios as Rosso pushed Barry to bond with him, promising that his strange blood-based rejuvenation powers coupled with his super-speed might help Barry find a way to survive the coming Crisis on Infinite Earths and his prophesied death. While it seemed at first that Barry was successful in fighting off Rosso's attack, it was revealed at the end of the episode that Rosso was successful in taking over Barry Allen's body, which generated a black-tinged lightning when he used his speed powers. More, the same black-blood substance that Rosso secreted as Bloodwork now covered Barry's eyes, lips and The Flash emblem on his costume.
Many fans of The Flash comics were quick to comment that this new look for Barry resembled a recent story in the comics, where Barry Allen became the Negative Flash. This occurred after Barry Allen absorbed the Negative Speed Force which empowered the Reverse Flash and the negative energy began to affect Barry Allen's powers, making them more destructive and entropic in nature. Tapping the Negative Speed Force made Barry Allen's skin paler and turned his lightning black. He was in serious danger of dying due to the influence of the negative energy upon his positively charged system until the Negative Speed Force was stolen from him by Meena Dhawan - another speedster and former STAR Labs scientist once known as Fast Track, who took up the Negative Flash mantle.
Fans could be forgiven for making a connection between the Negative Flash from the comics and the new design for the Bloodwork-possessed Flash. Rumors of the Negative Flash appearing in the show have run rampant since a series of photos showing the new costume were posted on Twitter and there is a strong resemblance to the Negative Flash design from the comics. It also makes sense given that Ramsey Rosso was introduced into The Flash comics during the same period of time that Barry Allen was trying to free himself of the Negative Speed Force.
However, there is nothing to indicate that Barry has tapped into the Negative Speed Force. This evil counter to the energy that empowers all speedsters was introduced into the lore of The Flash TV series last year, after the Reverse Flash Eboard Thawne taught Nora West-Allen how to tap into it. While the costume designers may have taken inspiration from Barry Allen's darker, more disturbing appearance in the comics, Barry Allen has not truly become the Negative Flash.