Well there are two Vergils:
DMC 1
DMC 3
DMC 1 Vergil noone never knew much about how he was. But Dante's memory tells us that Vergil was as joyful as himself.
And Dante told Nelo Angelous "It's a shame someone like you work for Mundus".
DMC 3 Vergil seems like a copy of Sesshomaru from Inuyasha.
He later went again to Underworld to save the girl named Rin.
Human psycology isn't rocket science, something you've watched or been around leaves a pattern on you later when you create something such as a character.
DmC is punk influenced because that's one of things Tameem grew up with. Other influences: Inception, V for Vendetta etc.
With that said Inuyasha is a famous manga, and considering i am not japanese and find it really appealing it makes you wonder how popular it must be to Japanese people.
And japanese people made DMC 3 and it's character Vergil.
And it goes back to Vergil being a Sesshomaru inspired character, and considering Sesshomaru cares for a human called Rin (even though he doesn't have to), then that same "character" trait applies to Vergil.
Because let's face it, the little we see of Vergil from DMC 3 he does not come off as evil.