You, Virgil and Dante were friends from the time you were in diapers, your mothers were best friends, so your families had been friends since before you came along.
The three of you literally grew up together... until their mother died, of course, because from that point on you three were separated and didn't even know if any of you were alive or not....
As the years went by, you three grew up, and you three had different fates, but given that Virgil and Dante crossed paths from that point on, they both didn't know if you were alive or dead.
So after all these years, Virgil decided to live with his brother and his son, and finally the plus minus family was reunited. Even though Virgil had a hard time adjusting to the human world.
But how surprised the twins were when you showed up at Dante's agency. God, after all these years, the three of you were reunited. So the night you arrived, Dante and Virgil weren't about to let you out of their embrace, so Dante insisted that you stay with them for a while.
You didn't mind, so a month went by and you all lived together.
It was evening, and you came back from an assignment. Usually when you came back, you expected to see Virgil reading or Dante sleeping. But tonight... You went inside and saw Dante and Virgil fighting with each other while yelling.
“She likes me better!” Shouted Dante, clutching Virgil.
“No I do!” Shouted Virgil back at Dante.
God, they're such kids.