10 Arrowverse Villains Who Were Actually Heroes

Hartley Rathaway was a former STAR Labs employee who was fired by Harrison Wells (Eobard Thawne in disguise) for attempting to stop the activation of the particle accelerator due to its risk of exploding.

This left Rathaway resentful of his former mentor, and, upon realizing that he obtained abilities from the explosion, he sought to get his vengeance on Wells and STAR Labs as a whole.

Naming himself the Pied Piper, the embittered prodigy attempted to drive apart Wells and Team Flash then take them down, only being foiled by the combined genius of the resident STAR Labs team and Wells/Thawne's deception. He was captured by the heroes and later escaped by taking advantage of Cisco's guilt over Ronnie Raymond's death.

Despite this, Rathaway helped the team on two separate occasions - during their time battling Zoom, and in the post-Crisis timeline battling Godspeed when Flash lost most of his speed, for which the help was in exchange for Team Flash helping Hartley restore his boyfriend's health.

These instances showed a kinder, more heroic and caring side to the character that was only hinted at in his early appearances.