Please read the narration in Bukhari that Imam Ali is the first one who will ask justice from Allah in his case at the day Resurrection. We all know well that Imam Ali was the real successor of The Holy Propeht. He was deprived from hi srights after the death of The Messenger of Allah. Imam Ali is the central figure of Islam after The Prophet. But he was put in the cornor.

 Please read our article who are the central figures of Islam and other articles about Caliphate.

http://sunnah.com/bukhari/64/18