What is the relationship between Yoruichi and Soifon?

Yoruichi Shihouin shares a close friendship with Soi Fon, which is not limited to their leader/subordinate relationship. Soi has some romantic feelings for Yoruichi that have been reflected many times in her actions, such as buying Yoruichi's skimpily dressed photos.

The friendship between the two had got strained when Youruichi Shihouin decided to leave the soul society without a valid explanation. This led Soi Fon to develop hatred towards anyone who failed to obey orders or created disharmony in the soul society. However, the pair became friends once again during the "Rukia Rescue" story arc, after Soi recollected her feelings towards Youruichi.