Wentworth Miller makes his Arrowverse return in this season's crossover event, but this time he'll be playing Citizen Cold rather than his more familiar, and villainous role of Captain Cold.

Fans of The CW's Arrowverse were dealt a bit of a blow earlier this week when Miller hinted that he would soon be departing from the role of fan-favorite character Leonard Snart, aka Captain Cold. The character first appeared on The Flash as one of the Scarlet Speedster's classic rogues, a brilliant thief with a heart of ice. Throughout his appearances, Snart began to show compassion in his own way, and a softer side to the villain was slowly revealed. Eventually, he would become a genuine anti-hero after joining the ranks of DC's Legends of Tomorrow, a series that saw Cold make the ultimate sacrifice to save his friends and the universe, fully cementing his turn from villain to hero.

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Another, earlier version of the character, a Captain Cold who was as villainous as he was devious, would eventually surface on the second season of Legends thanks to the series' time travel core. Though fun, fans missed the Snart they had come to know and love, and now, before Miller says goodbye to the character, it looks like he'll finally get to play the character on the other side of the spectrum, as a full-on hero.

The synopsis for the Arrowverse's next crossover event, "Crisis on Earth-X," revealed that none other than Citizen Cold will arrive to lend a helping hand to The Flash, Supergirl and the rest of the Arrowverse superhero gang. Of course, that raises the question of who Citizen Cold is, and what's the difference between him and Captain Cold?

Citizen Cold first appeared in the pages of the 2011 DC Comics event series Flashpoint, by writer Geoff Johns and artist Andy Kubert. The Flashpoint was an alternate timeline reality which came as the result of Barry Allen traveling back in time and choosing to save the life of his mother, and would eventually become the basis for the third season of The CW's The Flash. This world was drastically different than the one Barry Allen knew, one where Aquaman's Atlanteans and Wonder Woman's Amazons waged war on a global scale, and one where Barry never became the Flash. In his stead, Central City had a very different hero to protect it: Citizen Cold.

In this reality, with no Flash to fight for Central City, Leonard Snart, armed with his iconic freeze gun, became the hero of the citizens. Much like the Flash, he took the fight to the Rogues, and he had a museum dedicated to his heroic deeds. This was still Leaonar Start, though, and Cold was a much more brutal hero than the Flash ever was, going so far as killing some of his villains. However, in such a bleak and hopeless world, these tactics were not necessarily worth condemnation, though some of his detractors tried. But at the end of the day, to the people of Central City, Citizen Cold was their greatest hero, a man who fought to protect the people in a dark world.

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With the third season of The Flash having already explored a storyline that borrowed many elements from Flashpoint, it's a safe bet that the Arrowverse's version of Citizen Cold will hail from a different place -- possibly, a different universe altogether. Parallel Earths and alternate versions of established characters have become sort of the norm around Barry's parts, so there's a good chance that Citizen Cold could arrive on the scene from another universe. If Earth-X features the greatest heroes turned nazi-fied villains, then perhaps the villains, like Cold, are the true heroes on this world -- one that looks like a very cold place, indeed.