The first time Dick called Bruce Dad, Bruce practically melted, and enveloped his son in the largest hug he could.
The first time Jason called him Dad, it was after a fight, and they were already hugging. Bruce just smiled and wiped his nose.
The first time Tim called him Dad, Bruce cried, because this war of theirs had already cost Tim his real father and Bruce didn’t feel like an adequate replacement.
The first time Stephanie called him Dad, he got very confused. What do you mean, Stephanie, you have a father, he’s still around, but she just hugged him tight and said, no, he’s not my dad anymore. You are.
The first time Cassandra called him Dad, it was quiet, and subtle. The only acknowledgment was a nod of recognition on both sides.
The first time Damian called him Dad instead of Father, Bruce nearly had a heart attack. And immediately ran to grab a thermometer to make sure his son wasn’t sick.
The first time Duke called him Dad, it was a little hesitant. Bruce took him aside and explained to him, gently, that it was okay if he didn’t feel like a part of the family yet, he didn’t have to call Bruce Dad if he didn’t want to, but Bruce would always consider him his son. The second time Duke called him Dad came shortly after that, and Bruce cried.
The first time Terry called him Dad, Bruce asked him not to, because Warren McGinnis was the boy’s father for every purpose except genetically and Bruce didn’t want to take that away from him. Terry was secretly glad when Bruce explained this.
The first time Hal Jordan called him Dad, it was by accident in the middle of a firefight. Both of them stared at each other, and immediately agreed to never speak of it again.