I saw your comment in the DmC Supporters Group.
My theory is perhaps, prior to Devil May Cry 3, Vergil rocked an 'emo' type image, through being traumatized by what happened to his mother, considering her murder. He was somewhat sent crazy and perhaps even hospitalised at a Mental Hospital for his insane actions to other beings. Afterwards he may of broke free, and killed humans out of anger, sending him to prison to have his picture taken by the police, before he went nuts and took them out. Just an idea. Him pretending to be Dante could just be to set Dante up, or through part of his insanity. Just an idea.