User blog comment:Sinister 00/About 666/@comment-4547267-20140113012347/@comment-213.106.131.123-20140129223618

I think 666 will be like Ophis, a shape shifter, I also think it will be some kind of spirit and needs a vessel to possess to use it's ture power and it will turn out Issei is that vessel. When Issei gets possessed his eyes become black with a glowing red upside down pentagrams, he will get a black tattoo like upside down penatagram on the top of each hand, three red six's running vertically up his back and the the word Trihexa burned into his forehead.

p.s. For some reason when possessed the clothes on Issei's torsso disintegrate.