Thinking about it, I've always been interested in the history behind "Tony Redgrave". Didn't Kamiya say that he was a journalist that Dante respected and so used his name as an alias? He could be investigating the demons and comes across a younger Dante.
Or alternatively you could go the route of the non canon novel where an amnesiac Tony Redgrave (Dante) is discovering his heritage via the antagonistic Gilver. In fact an adaptation of that novel would probably be the safest bet to draw people in.