However unrealistic this might be, I'm rather fond of this pairing...
Drabble #25: Hisagi Shuuhei and Urahara Kisuke
Once the war was over, life had stabilized once more. Hisagi Shuuhei took to using his leave time to visit the Human World. And it wasn't - as his friends thought - because he was a workaholic keeping tabs on Urahara.
It began as a way of discovering more about his new taichou covertly. But then Urahara recommended a music store. Somehow, the next thing he knew, the blond was rigging Human technology to work in Seireitei - and Shuuhei realized he was fond of the irritating bastard.
When they kissed, things snowballed out of control and into the nearest bedroom.
A/N: Yes, it is canon that Urahara modifies human tech to work in Seireitei. Hisagi rides a motorcycle (it's mentioned by Renji), Shinji has his music, etc.