User blog comment:B214/Talk About What You Want! 2/@comment-99.196.4.193-20140924011134/@comment-99.196.4.193-20140924014313

Ravel started researching about Issei after Rias and Raiser had their ratings game and then started falling for him before actually approaching him.

I was thinking about someone who really wants to kill Issei. Like maybe an angel that fled after the "Three Powers" united (I could be wrong but I don't remember reading that the angels who worked to sabatage the meeting became fallen) or possibly a fallen angel that was unhappy with the "Three Powers" working together or some unkown.