41 years ago - Mick Rory is born.
29 years ago - 12-year-old Mick's accute pyromania leads him to burn down his family farm. He is placed in child services.
19 years ago - 22-year-old Mick is caught while on a hiest. He blames Leonard Snart, but keeps his mouth shut.
17 years ago - 24-year-old Mick is released from prison.
15 years ago - 26-year-old Mick is approached by Leonard Snart to use his fire harness. He becomes Heat Wave and joins the Rogues, challenging the Flash, remaining loyal to Snart when Roscoe Dillon challenges him for control.
13 years ago - 28-year-old Mick sides with Leonard Snart when he allies the Rogues with Barry Allen & Wally West to stop Eobard Thawne's takeover of the Rogues after he kills Lisa Snart & Sam Scudder.
11 years ago - 30-year-old Mick & the Rogues ally with Gorilla Grodd until his plans become evident. They then help Barry Allen & Wally West stop him.
7 years ago - 34-year-old Mick is caught & sent to prison by Wally West when he ends Barry Allen's ideal with the Rogues, holding them responsible for the fall of Frankie Kane.
6 years ago - 35-year-old Mick escapes from prison with Leonard Snart, working to restart the Rogues.
3 years ago - 38-year-old Mick helps Leonard Snart stop Clifford Devoe's new, more lethal team of Rogues, earning a new deal with Wally West.
While generally the idea of the Rogues, the organized group of Flash Villains, is mostly atributed to mark Waid's early 90's series, he didn't come up with it in a vacuum. The idea that this particular group of bad guys has a stronger than normal sense of community has been around for most of their history, it was just formalized in the 90's. One of the best examples of this was Heat Wave, a character that was really created as an answer to the question "what would the Flash's arch-nemesis's best friend look like?"
Heat Wave's Comic History
Heat Wave debuted in 1963, designed as a deliberate counterpoint to The Flash's nemesis, Captain Cold. As gimick-villains go, he's actually a pretty straight-forward one... if you're going to make your villains little more than a dude with a weapon, you can probably do worse than a flame-thrower.
What made the character interesting was the way he fit so cleanly into the notion of the Rogues. He was basically an uncomplicated thug, but that simplicity of character made him a great foot soldier for what evolved into a family of villains. As the Rogues started walking the line between being enemies and allies of the flash, he's become a sort of vague anti-hero. We've even seen the character join a live-action team of superheros in the show Legends of Tomorrow. That's a weird thing, but it speaks to the flexibility of the character that he seems to fit into that role without too much effort. He's defined by his loyalty to the people around him just as much as he is by his pyromania.
Our Heat Wave Story
While there are quite a few minor variations on Mick's origins, we actually find that the simplest route is best. He's not a complicated character. He's a violent pyromaniac that also has a strong sense of loyalty. That's pretty much it. To that end, we've just tied his backstory to Leonard Snart, as that relationship has always made the most sense. He was a part of Snart's gang long before he ever put on a costume and threatened a superhero. Snart made him his flame weapons because he knew Rory would use them to great effect. His career isn't as a crook or terrorist; He's an enforced. He lives to protect the Rogues.
What happens next with Rory is actually kind of interesting; because it actually really hinges on what happens with Snart. It sort of makes sense that one of them might become less and less of a bad guy, and if that happens, you have to wonder if the other one will follow suit... or become all that much more dangerous as they loose their partner.