Thrash was born as one of the last Mobian Tasmanian Devils, a race which had been mutated into Mobini Devil Dogs by Echidna Albion scientists during the Forgotten War. Over many generations their race produced less and less full-blooded Devils to carry on their line, thus leaving Thrash as perhaps the last known Mobian Tasmanian—in fact, his two sisters were born Devil Dogs. At some point in his life Thrash decided to set out on his own quest to find and exact revenge upon the Echidnas with his two sisters, but achieved little, and decided to join the Downunda Freedom Fighters to "bust up a few heads for a good cause." (SSSM: #2, SU: #11, CSE)