Creation
Mayor Rob Morrisroe was introduced into the DCU after the relaunch of 2011. He was created by George Perez as the new Mayor of Metropolis. It’s never revealed what happend to Mayor Fleming but it’s most likely that she was erased because of the relaunch.
Storyarc
After Superman saved Heather Kelley and the other missing persons and he killed Titano and some criminals, Mayor Rob Morrisroe is still a supporter of Superman.