Byakuya Kuchiki
She was the slip of girl his younger sister had dragged home from the academy one day for a study session.
In the end he ended up calmly dirking tea with her while they waited for Rukia to return from tracking down Renji.
It was awkward at fist but as time went by and they found themselves having tea more and more often with each other, eventually they began exchanging pleasantries and soon they no longer needed Rukia to invite her over, he did.