Mick Rory,
brought into the Flash series as a villain with his partner in crime Leonard Snart. In his childhood he became fascinated with fire, so basically he had pyromania and one night his obsession got out of control because he burnt down his family's home, which killed his family members.

His nickname is "Heat Wave" named by Cisco Ramon. His main goal is to steal because it's a lot better and easier than working. He is addicted to fire which is why he has a fire gun. In 2016, he was one of the eight recruited by Rip Hunter to stop an immortal villain Vandal Savage. However, the change in him happened when he traveled through time with the Time Masters as a bounty hunter Chronos and that's when his journey became clear, kill Vandal Savage while still making time to do some thieving. He does have a secret though, he actually cares more than he lets on which he told his Ray Palmer. He threatened to shave Ray Palmer's hair if he told anyone his secret caring feelings.

Additional, after the death of his best friend of 30 years in Leonard Snart, that is when his character growth officially grew. It's a death he never got over but when his best friend sacrificed his life for his, it changed everything for Mick because first he couldn't believe someone would do something so stupid but second because it forced him to be way more than just a shadow trailing behind someone. He got to really develop a bond with each person. Like for example, with Ray he already had a minor friendship with but than came Amaya, who believed him and stood by him through the worst things. Even when Mick joined the Legion of Doom because he saw a Leonard from the bad, she still believed in him. It's a belief that Mick was never use to anyone having in him.

Finally, after not fitting in anywhere, loving the wild dark side, betraying his legends team twice and pretty much not having any future plans, he finally officially found his family and future in being a legend. He finally found his home where he completely fits in with. He went from being an uncontrollable wild case to being a wild case who really loves his teammates. and wouldn't leave any of them to die in the hands of anyone.