Timmy
His parents had called him Timmy when they were around. They said it the same way they might speak of any other expensive item: proud but detached in a "look at what we have" way, without any actual interest in him as a person. They were a married couple, so they had a kid. Box checked. But they didn't actually know what to do with a kid, didn't know anything about him, so the baby-ish name stuck.
With the Bats it was an affectionate nickname, sometimes teasing or joking or cajoling, but always personal.
(They used it less after Damian.)
Tim kills me. And I kinda want to kill his parents half the time (including Bruce).