This issue is a lot of headache for someone who hasn’t done a reread of a lot of previous issues, especially since the panel orders in this comic issue are arranged from present time then all the way back to the beginning, explaining how Thomas Wayne became Batman in his Earth, and why he’s doing everything to stop his son Bruce from continuing to be Batman.
Here we learn that it was the Reverse Flash who saved Thomas Wayne as his Earth came to an end.
From – Batman Vol. 3 #84
