Disclaimer: Most of these things don't belong to me, unless I'm J.K. Rowling and no one told me. In which case, some one owes me a lot of money.
Niger Ovis (Black Sheep)
Prologue
The Potters retuned with Dumbledore to the remains of their cottage after celebrating Halloween with some friends. Peter, a close family friend, had been left to care for the boys, as he was not a fan of parties. There was no sign of Peter as they took two small boys from the smoldering wreck that, up until that Halloween night, had been their home.
Dumbledore inspected the two boys, looking at the magic aura surrounding them. He noticed that the magic came off in strong waves from the bundle named Jason while Harry's aura was almost non-existent. With this knowledge, he deduced, without a hint of a doubt, that Jason was the boy-who-lived. The jagged 'S' scar on his forehead only added to this theories credibility. He will mark him as his equal. The line from the prophecy, and wasn't the 'S' a symbol for a snake, a symbol for Voldemort? The lighting bolt scar on Harry's forehead was probably a backlash from the powerful magic released by his twin that had wounded Voldemort. Dumbledore talked to the Potters for a moment and the three figures disappeared with their bundles.
Later that night, Dumbledore would explain the situation to the Potters while seated in the sitting room of the Potter Mansion. James Potter would need a large glass of brandy when told that one of his sons had defeated Voldemort and would now be a target. Lily would faint and would need to be carried to bed. They would soon separate the boys, for Jason's own good of course. Jason would be showered with lover and affection while Harry would not.
It is very interesting how Dumbledore gauged who the boy-who-lived. If he had look more closely at the auras, he would have noticed two distinct things. The first being that Harry's showed signs of magical exhaustion, which usually appeared after a powerful spell was performed. His aura was not weak, just drained. The second thing he would have noticed is that the magic Jason was radiating was not his own, but rather the result of being at a place where a powerful spell was performed. If he had inspected the bodies of the two boys more carefully, he would have noticed two more rather significant things. These being that Harry's scar was the result of a magical spell while Jason's was not. It is a pity Dumbledore missed these facts, as it would prove very harmful to his plans in the future.