ok I was reading threw Wiki and saw what they had down for Yoruichi's and Soifon's relationship and thought I'd put it up here see what you all thought about it. (Yoruichi's and hers is the only one talked about for Soifon.. Also there is none talked about for Yoruichi ( http://bleach.wikia.com/wiki/Yoruichi_Shih%C5%8Din )
Yoruichi ShihōinMain article: Yoruichi Shihōin
Soifon's relationship with Yoruichi is one of the more dynamic among the Shinigami. When Soifon first laid eyes upon Yoruichi when she was young, she likened it to looking upon a goddess.  Soifon admired Yoruichi's strength, beauty, and nobility to the point where it passed admiration and became worship. Soifon worked her way through the ranks and was personally asked by Yoruichi to be one of her bodyguards. Being with Yoruichi made Soifon happy. However, one day Yoruichi left without warning. Such an action devastated Soifon to the point where she felt betrayed. From that moment on, Soifon trained herself to become stronger so that she could arrest Yoruichi herself. When Yoruichi returned to Soul Society, Soifon battled her to prove her superiority. However, Yoruichi was the stronger. Seeing this, Soifon broke into tears, wondering why Yoruichi didn't take her as well. After their fight, they reconcile and re-establish their relationship. In several omakes, Soifon's relationship with Yoruichi is portrayed as childish and somewhat obsessive.
link to Soifon's info