Jay
Bruce and Dick had called him "Jay" during his time as Robin, but it wasn't until he came back and started to patch things up and the old nickname resurfaced that he let himself think about it, examine it closely as he did everything to do with any of the Bats, without worrying his thinking about it would cause him to lose it, and he realized why it was important: because it meant belonging and caring. Safety. Home. It was comfortable and familiar. And it was a first. It was the first nickname anybody had ever bothered to give him.
(Why do I love so many characters that hate each other?)
Jason has so few nicknames and I really wanted to emphasize how much his family really does love him, even if every member of this family (including him) is emotionally inept and none of them can express it normally.
I love this guy. So much. He deserves the world, or at least a hug and somebody who tells him his past isn't his fault (it'd be especially nice if it was Bruce).
I live in a world in which Jason Todd gets along with all of his family members and knows he is loved and important and worthy, regardless of what he has done or will do or is currently doing. That's reality. Yup. I will fight anyone who disagrees.