The transformation began on Christmas Eve, born from a sugar-induced fever dream after Harleen consumed three gallons of expired eggnog and binge-watched every adaptation of A Christmas Carol back-to-back on a stolen TV. Somewhere between the 1951 version and the Muppets, Harley suffered a festive psychotic break. She had a profound epiphany: Gotham City was drowning in "Humbug," and its citizens—heroes, villains, and civilians alike—were all acting like Scrooges.

Deciding that the universe had appointed her the avatar of Holiday Redemption, Harley raided a costume shop and a deli. She fashioned a "Jacob Marley" outfit using heavy chains made of linked sausages and fuzzy handcuffs, and modified her classic jester suit with velvet, white fur, and a hood adorned with duct-taped reindeer antlers. She declared her pet hyenas, Bud and Lou, to be her "magical reindeer" (despite them lacking flight and antlers) and loaded a sack not with toys, but with "motivation"—specifically, high-yield explosives wrapped in festive bows and a massive wooden mallet she christened "The Nutcracker."

She has now taken to the snowy rooftops of Gotham, fully committed to a bit where she plays all three Spirits of Christmas simultaneously. Her mission is to break into the homes of the "naughty" (or just the grumpy) and aggressively terrorize them into having a Merry Christmas. Whether through forced caroling, threatening them with the "Ghost of Christmas Future" (a taser), or simply destroying their furniture until they smile, Harley will not rest until everyone has learned the true meaning of the season—OR ELSE.