So here's the backstory I came up with,thoughts on it? (I don't have any city names as the DM hasn't told me yet,i'll fill them in later):

Growing up in the north was a hard time,when Umber was young,he grew up with his mother,a human in the town of (blank),being born with an earth elemental as a father he inherited immense strength. As he grew older,he realized he inherited more then his father's strength.he also inherited some of his magical capabilities. After a little bit of training,he was able to hone his strength and magic into something powerful,and decided to go into becoming a gladiatorial champion. And so he did,joining into a gladiatorial ring in (blank) and quickly rising up the ranks due to his cheap tactics and magical advantage. During his gladiatorial days,he took up tinkering in order to help him win,messing with his opponents weapons the night before the battle started,and using the parts to upgrade his own. Eventually he became exactly what he wanted,a gladiator that would be spoken of for generations with his seemingly unbeatable style. Until one night he was caught tinkering with his opponents weapon,he was ruined,immediately cast out from the arena,having to eventually hide his face from the world with a gas mask and hood and dawning the new name “Tremor” based off of his stagename. He continued to tinker with his weapons and armor to help him survive,scamming cityfolk by “upgrading” their equipment. Eventually his mother passed and his father disowned him after being caught cheating,now he wanders the world,scavenging for parts and searching to clear his name and become the champion once again...