The Vergil cutscenes in DMC4 take place before even DMC3 timeline wise.Did Capcom (and everyone else forget) that Virgil became Nelo Angelo and died at the end of the first game? How is he back in DMC 4 (and supposedly 5)? And if he did return post DMC 1 he should look and have the powers he did in DMC 1 not 3 (which was a prequel). Is this ever acknowledged in game?
As far as Vergil coming back for DMCV... most people don't think he actually died in DMC1.