The Queen of Askadel
It was finally revealed that Isis was responsible for the murders in Mu and that she did so in her plot to attain the High Throne. For some reason, she pushed Hero to take his place on the throne and she continues to have a vested interest in him. Since the Rebellion and the Organization now know that Isis also murdered Elaine and made an attempt to have Sally murder Fate, they're unclear as to why she was so hell-bent on rallying Hero to her side. She has also expressed an interest in befriending Bedad, which makes Jackyl worry Isis may wish to take control of the Universal Virus "Akira."
Jackyl also believes that Isis ran off with one half of Fate's soul during the start of the Battle of the Capital and that she may be doing so to kill off the Three Fates, given that Mortis also murdered Abyssus.