Paternal
It was ironic (and depressing) that only the children Bruce had the most difficult relationships with called him anything vaguely paternal.
Damian called him "Father," distant and tentative even while he clung to the genetic relationship as if it were the only claim he had to Bruce.
Jason called him "old man" or even "Dad," always bitter, challenging, mocking, as if Bruce hated the familial connection as much as Jason did and throwing it in his face would annoy him.
Stephanie called him "Dad" sometimes, sarcastically, as if she could never actually be cared for as one of his own.
I know there are perfectly valid reasons why pretty much no one ever calls Bruce "Dad," but once I made this observation it wouldn't let me go.