Jason's favorite thing to do when he was six or seven was take tires off cars, especially tires that looked fancy and expensive.
Then he took the Batmobile's tires off and sold them for cash. Too bad no one would buy them.
When Batman came looking for him, all he could do was behave and let himself be taken to Wayne Manor as Bruce's adopted son and the second Robin.
What did you think would happen if you went around taking people's tires off?
And then... he ran away.
