Leo Valdez and Annabeth Chase.
Okay, romantically is a hell no because I just... No. Hell no. Nah. That'd be weird.
But honestly... I'm imagining the two on a date and for some reason that's also hilarious to me because Leo would just reluctantly flirt while Annabeth just... wouldn't have any of it.
But, if the two actually ever did work together, I feel like they'd actually be a pretty good team. You know, when Leo actually is serious.