Chris: "Everyone knows Batman and Robin."
Robin: "Nobody in their right mind would ever want to be Robin in that scenario."
Chris: "But what if... Robin was a chick? mindblooooooown"
Robin: "Then everyone would want to do Robin, not be Robin."
Chris: "Exactly!"
That there is some first class, subtle as hell, flirting!
Chris makes a big deal about MC being the smooth talker, but Batman(Chris), in three short sentences, told Robin that...
1. He wouldn't mind being partnered up with her.
2. That she if she was the Robin to his Batman, it would be mindblowing,
and
3. Agreed that she's hot enough that EVERYONE would want to DO her, in other words, he's cool with Kira.
and, Kira heard it all as they walked away.
You have to read between the lines a little, but it's all there.
Solid set up to a future relationship and a better Meet/Cute than many movies have!