All it would take were two words and a green light for the boy to die and then his reign over Britain would start.
Avada Kedavra. Let the thing be destroyed.
He remembered the first time he said those words. He had his wand against his biological father's heart and it seemed to him as if it had just been that same afternoon instead of years before. For Lord Voldemort, casting the killing curse felt natural. Like the feeling of his heart beating strong and steady after a long day of fighting.
This time it wasn't the same. His trembling hand didn't let him raise his wand against the boy. His palms were sweaty and his mouth dried suddenly.
He stared at the boy for a full minute, watching him breathe softly without a single tear. How could the boy be so calm after he had just killed his mother?
The curse had come easily with the mudblood; a poem out of his lips. But not with the boy. He wasn't restless, as any other infant would be at sensing its mother dead before their eyes. The little Potter boy was daring him to do it.
When the peaceful boy glanced at him he didn't see the knowing eyes of despair all his victims had. He found, instead, a focused stare that was unnatural for a boy of his age.
He couldn't. He wouldn't.
A killing curse for the boy never left his lips. Green, blinding light was not shot out of his wand at his command.
Instead, strong arms picked up the boy.
"Grow and learn," Voldemort told the boy. "You will be my equal someday."