Disclaimer: I don't own Harry Potter or people of that world, I just own Lucas Potter.
In the house, two babies awoke. One, drained from playing with the light, decided to go back to sleep. The other hit his cheek on the corner of the crib and started crying.
The wards flared as they let in another visitor, Albus Dumbledore. He rushed into the house along with Sirius Black, the Potters' best friend. Remus was off on another mission. They entered the front door, and saw a bloody James Potter trying to sit up, and wincing because of the glass. Sirius rushed to his friend's side, who said, "Lily... Harry... Lucas... Voldemort... Help them." And with that he fainted. Sirius got him on a stretcher and Apparated him to St. Mungo's while Dumbledore checked upstairs.
He found Lily waking up, and together they went to their boys. "Lucas and Harry are safe!" she cried out in relief. Hugging the now quiet Lucas and Harry, she spun around to Dumbledore.
"Where is James?" she asked, worry alight in her face.
"Do not worry," the headmaster was quick to assure, "he is fine. Just some broken glass and a concussion from an explosion. Now may I see Luke?"
Lily frowned. "What?"
Albus sighed. "Look at Luke's cheek Lily." There was a bloody cut, that if looked at in the right angle, was a 'V'. "He has defeated Voldemort tonight. All hail Lucas Godric Potter, the Boy Who Lived!"
No one knew just how much Dumbledore's first big mistake would cost the world.