well heres how i understand it
-2000 years ago sparda batteled and sealed mundus in the underworld
-short time after he aided the people on the island of DMC2
-sometime after that he sealed his powers and the demonic world useing the blood of a prestess. and becomeing mortal
-closer to our time he met and married eva
-sparda had the twin sons who were half demonic blood
-sparda died of unknown resons
-demond attacked spardas home and killed eva most likely in serch of the amulet and to rid the world of the sparda bloodline.
-dante and vergil grow up after escaping the demons
-dante opens his store which is attacked and destroyed
-dante defeats vergil in hell
-vergil stays in hell and battles mundus and loses with his soul trapped in hell he becomes nelo
-dante opens a new shop which he names devil may cry
-dante meets trish and they head to the island to battle mundus
-dante defeats nelo but it is speculated that he wasnt killed in the final battle
-dante defeats mundis and escapes with trish
-dante renames store to devels never cry.
thats what i think anyway we will just have to wait for the games/capcom/novels to confirm it/