From reluctant cooperation to teamwork to possibly more. I dunno, the image of exasperated Shiki trying to teach Izaya stuff and ending up with a total clusterfuck amuses me sm
One unexplored shikizaya dynamic I really hope to touch at some point - master\disciple. In a fantasy au so we'd have them doing fun stuff like martial arts\magic or something like that. So Shiki could be Izaya's (or Kanra's) Friren\Obi-Wan\Haymitch.
Add the slow burn pent up tension bc Shiki sets frigid boundaries and doesn't react to provocations. Until external forces push them out of their roles and throw them on a battlefield where paradigm shifts forever.
MAIN thing that always hooked me on them - those are TWO social PREDATORS, circling each other. Both dangerous, just in different ways. Equals. Neither is a victim.
Truth is if Izaya had been voiced by anyone else and I've never read the novels I'd dismissed him the same way as the rest of annoying cartoonish entps out there.
Kamiya gave him depth and humanity. VA truly makes 70% of the character.