How unoriginal. She's his sidekick. He's the first person to pop into anyone's head when people think of people that Harley would have kids with. I say Deadpool is better. He's a much better match than Joker. To be honest, I think Joker is gay and just has Harley as his sidekick to convince himself otherwise. He's confused sexually. Why else would he keep an absolutely terrible sidekick that causes nothing but problems, and obsess over a man in tights?