You know, back when Loeb brought Kara Zor-El into post-Crisis continuity, Kara spent a chunk of time on Themyscria and had a very close friendship with Wonder Girl. I got to thinking that Kara would be a great "in-between" character, bridging the gap between the Super and Wonder franchises. Not just Superman in a skirt, not just another Wonder girl, but a bit of both and in that way, unique. I had ideas in my head of Kara wearing Amazon forged armor with the "S" shield and red cape.......
And I started wondering who else could tie the Trinity members together, who could be a legacy of two families so to speak.
Obviously Nightwing fits perfectly as the "Super-Bat" combo. He and Clark had a great relationship back in the day, Dick's name is taken from Clark's mythology, and Dick's time with the Titans makes him well suited for tangling with superhuman threats.
The "Wonder-Bat" connection.....no one ever really fit. Grace Choi, Cass Cain, a re-imagined Nubia......no one ever made sense as a character with one foot in Gotham and the other in Paradise Island.
But Ive wanted to see Dick spend more time with his "favorite uncle" in Metropolis ever since. That Jon has been around for two years and hasn't had the chance to hang with Nightwing is a crime against comicdom.