There's something so eerily familiar about everything that happens in the Harley Quinn cartoon.
First off, the characters (lesser known ones people could probably NEVER have heard of, sometimes) like the Deathstroke-esque Russian dude on the train who kicks her out, at the very beginning of episode 3. Who? I immediately recognized him from Robin. Remember Robin's original girlfriend? The Russian girl whose dad's (uncle's?) shop Tim helped save from the Russian Mafia? The one he went to school with for a while? I don't need to remind. Chuck WROTE it, we all read it. Nobody could have figured out KGBeast, but I feel like he was targeting a very specific audience, because at least to Robin readers, he DID have a lot of impact or value.
King Shark's been gaining a lot of popularity, and I'm 100% sure he belongs at Harley's side because obviously, SUICIDE SQUAD! However, the first thing that comes to MY mind when I see King Shark, is Watery Grave. Superboy manipulated his TK to copy strength, flight, invulnerability and a lot of Superman's powers. But whether post-Crisis or pre, Superboy seems to always have a problem with one specific power: HEAT VISION. One might even say that heat vision is the one power that defines a Superboy as a MAN. Twice in his life, Superboy has used heat vision. Once when Klarion messed with everyone's metabolism and turned the kids into adults, and once when he had these red shades, which he lost while fighting the Silicon Dragons, in Watery Grave!
Ok, so I'm drawing weird similarities and trying to approach a weird conclusion that I want (because people see what they WANT to see,...) but then comes the weirdest character in all of.... Frankie Muniz? Aka Malcolm in the Middle. A very awesome show, and made EVEN MORE popular after Hal (Bryan Cranston) did Breaking Bad. As Malcolm was a tv show from... mid to late 90s, going on into the 2000s, we could assume something very specific about Harley Quinn's age. Was she a 90s kid? She had a crus on him BEFORE she hit puberty, when Frankie was also the same age because they were either roughly the same age, or Harley was as young as 6 when Malcolm was 12.