For his Earth One equivalent, see Martin Stein.
After the particle accelerator explosion, he was exposed to the effects and merged with Ronnie Raymond. Ronnie resorted to trapping Stein within his body and refused to change back to their human forms, to the point where Ronnie could no longer hear Stein's voice. Eventually, Ronnie became a villain known as Deathstorm and started working for Francisco Ramon, the criminal called "Reverb", who worked for Zoom. He was later killed by Zoom when Ronnie nearly killed the Earth One Flash.