What do あなた think is the little 'secret' that Ivankov has on Crocodile?

I'm not sure, but whatever it is, クロコダイル, ワニ shut up pretty quickly, meaning that Ivankov really has something over him. As あなた said, it could that he used to be a woman, または it could be something もっと見る complex, but, whatever it is, we may never know and it will be a whopper if we do ever find out. XD

it's kinda obvious to me... just like Sanji, クロコダイル, ワニ maybe got trapped in the island of okamas and turned to a gay man... he freed himself somehow, and the only one who knows is Ivankuf