Snape and Lily were great friends. They also made friends with Professor Dumpbledor's daughter, name Emma. Snape couldn't win Lily's heart...but he did win Emma's heart.
Years later. Snape and Emma fell in love. Got married and had a baby girl, named Silena.
After Marcus Volturi found his new mate name Arana Cooper, they got married. And for a while, there was a little surprise for the both of them. Arana was pregnant with Marcus's baby.
This is before Renesmee. And the surprises will keep coming