Some people wonder how Obito knew how to control the Kyuubi and a various amount of other things. Well, assuming that Madara is the Aizen of Naruto, Madara planned it all out from the beginning. Then he showed it to Obito through that matrix thing he made when he was showing him stuff about the S06P and Madara probably told all his secrets to Obito too and everything he knew also.
Thanks for reading, kind of long lol. Any thoughts?