When Jason first gets to sit down on the passenger seat of the car with Bruce, as a civilian, Bruce doesn't notice it instantly, but his son's legs don't quite reach the bottom of the car — they are a tad shorter. He is a tad shorter. Then, in the middle of their road, a police car pulls them up, and the officer stares at the pair of clueless father and son and bursts out in the laughter.
"Sir... Mister Wayne, your son can not sit there. He needs to be back and at a special seat for children."
"Oh, he is not— Jason is too old for that."
"I am sorry. It is required by the height, not age."
Bruce turns around to face flustered, embarrassed Jason, who always insists that he is old enough for basically anything in this world, and he can't help it. He smiles, completely overwhelmed by this whole thing.
"Alright, thanks for warning. We will do just that."
As soon as the police are out of the picture, Jason bursts out in the string of complaints, whines, and genuinely distressed remarks about how he is not a child, never will be, and it is so stupid.
Bruce smiles all the ride back.
They still order him a child seat and he hates it.
The Batmobile from the other side doesn't have it, and they don't need it to.
Still, much later, when Bruce — Batman — opens the door, for the first time since Jason became Robin, he tries to settle his son on the backseat, not a passenger one. He cradles him to his chest before gently putting him on the leather couch. Jason's body is small and fragile, though this time his feet reach the bottom of the car. His head is lolling a little bit, and it takes two attempts from Bruce to prop it properly.
He ignores the blood that instantly spoils the car.
"My baby son," he murmurs softly, reaching to pat his curls. "My sweet baby."
This time, Jason holds no complaints. His bloodied lips with blooming bruises are pressed in a thin line, and Bruce closes his eyes, trying to ignore his cold, dead eyes.
He closes the door of the car and sniffles as his nostrils get scorched from the odour of the burning down warehouse on the background.