User blog comment:B214/Question and Answers 2/@comment-3965848-20140504123104/@comment-1359322-20140504140543

It's hinted to be because of Valerie.

"《For some reason, I felt that I needed to save this girl who is in possession of the Holy Grail. Very strongly, that is. That was a feeling different to my other self who is feeling indebted to her. ……Is this my gratitude towards her? I don’t know very well about it myself, but most likely, she had been using her power unconsciously even before it awakened completely. Even the fraction of Balor’s consciousness that became me is something she summoned by using the Holy Grail……and did she create me with it……?》"