Richtofen
Nein, not ze puppies!
In DMC 1 Dante said he knew he had demonic powers as a child and in DMC 3 Vergil stabbed Dante in the chest thus awakening his demon. So I'm not really sure how it's going to happen in this game...they might entirely by pass that and have his demon wake up in some other way instead of Dante being stabbed in the chest with his own sword.