It was a long story, but it had a very familiar beginning. One night, after finishing a day's work, Jason saw a super-cool car parked by the street, a car with four super-cool tires. Batman also saw a super-cool car parked by the street, but it only had three super-cool tires left.
This story was far too familiar to the members of the Bat-family. Yet Batman and Jason themselves had never told it. Batman had merely mentioned it one day while introducing Jason to Dick, but since the incident was too absurd even when summed up in a single sentence, it became widely known through Dick's retelling.
Strictly speaking, there had been nothing special about that night. Batman took Jason home, let him adjust to life at Wayne Manor for a few days, then brought him to the Batcave to teach him more professional combat skills, firearms handling, vehicle operation, mechanical control, and the Mechanical Engineering he was already good at.
The days of study were busy, and time passed quickly. Batman became the main theme of Jason's life, to the point that he soon forgot those days from his past.
But Batman was always busy. After Batman left alone, using Jason's young age as an excuse for why he could not go out and fight criminals, Jason would sometimes read by the fireplace, sleep in his room, cool off beneath the big tree in the garden, or stare blankly into space in the bathtub.
Then he quickly grew up, becoming an incredibly sturdy bird, until eventually he grew so big that Batman practically wanted to kick him out of the nest.
The time he had spent in that luxurious manor became the background music whenever Jason's emotions rose and fell, the wallpaper in his private chat with himself. He