Facepalming at:
Vergie.
V.
Pretty Boy.
Spikey Hair.
...Veggie.
I know the fandom tend to pick out petnames for their favourites, and that's okay. But when it comes right down to the actual writing, whether in fanfiction or roleplay... I mean... Dante wouldn't nickname Vergil any more than Vergil would call Dante 'D'. It's, to put it in Vergil-terms, Perposterous. Nicknames are for friends, a show of emotion of some sort, whether it be affectionate or malicious. The boys don't HAVE nicknames for one another. They are well above and beyond those borders.
It's VERGIL.
Nothing more, nothing less.