For those who don't know Thaddeus Thawne is the rival and enemy of Bart Allen the fourth flash and grandson of Barry Allen. I'm including a abbreviated version of his backstory but it deviates from canon quite clearly. I got the idea after thinking how alike Inertia (Thad) and Jaune look. Both are some of my favorite characters. Just to be clear to any dc fans out there Thaddeus did not kill Bart in this story so while Thad is Jaune on Remnant Bart has taken up the Flash mantle.
"I'm going to need both of you to do something before I tell you my secret." Jaune said to his closest friends Li Ren and Ruby Rose after bringing them to a empty classroom." I want you to believe in the impossible because that is what I am about to tell you." He looked at both of them. Confused and skeptical Ren nodded while Ruby stared at him before agreeing. He asked them to be here and not to tell Yang, Weiss, Blake, Nora or Pyrrha about what he would tell them. First to their surprise Jaune removed contact lenses showing gold eyes. Rena and Ruby at first mistook them for faunus traits.
" Your a faunus? Why would that matter Vomit Boy?" Ruby asked before Jaune removed several pieces of armor and soon began to run. Green lightning surrounded him in a protective aura he generated. He was a blur actually running on the ceiling and walls. When he was done his clothes were actually smoking.
" My name isn't Jaune Arc. My real name is Thaddeus Thawne and I might be the fastest man alive on Remnant." He stated to their surprise." Jaune Arc never existed but I took on this facade soon after the Arcs took me in. My entire life I lived before I found them was cold and empty. No one cared about me and what I really only knew instead of love was a mission given to me from people blinded by hatred. My birth family the Thawnes hated the Allen bloodline a family we antagonized for years killing the people they loved and taking away the joy they found. They were the heroes we were the Reverse." He said ashamed. Ruby didn't care about what his biological family was she cared about the person she knew. The person who was pouring out his deepest secrets right now. She was saddened about what he went through but glad he was able to break free from the cycle of this family feud.
" Bart Allen grandson of a hero known as Barry Allen inherited incredible speed and was part of our bloodline. But my grandfather couldn't get the chance to corrupt him so he created a copy with a strand of hair and mixed around the genes. Bart Allen grew up in a Virtual Reality to hep with his powers toll on his powers. I grew up slowly missing out on a childhood and love. Then when I was ready I was tasked with making him suffer. I captured him and took his place. Becoming an ideal better version and planned on killing his mentor then him." Ren never thought his brother like figure would even think of taking a life. Sure Jaune was showing skill in killing Grimm since his partner began training him but Jaune never even fought Cardin. He didn't show much improvement in combat class.
" Then I saw them how they actually cared and one of them actually offered to help me. Seeing on what family was supposed to do to each other I ran till something brought me to the Arc Family. By the time they found them I was hungry, desperate and attracting Grimm with negativity. " He smiled sadly." Edward and Linda Arc were patient with me. No matter how reclusive or how bitter I was. They fed, talked, and helped me. Made up a lie saying a relative abandoned me and soon their daughters treated me like a brother. I got the name Jaundice after remembering a another word for yellow and called myself Jaune and took the Arc name. Soon I had a new dream to be a huntsman. I felt that I needed to redeem myself. To bring some good into this world after my family brought so much suffering."
" That's when you got your false transcripts and got here." Ren guessed and his friend nodded. " I had no past legally on Remnant so I could never enroll at combat school. In hindsight running thousands of miles away, taking the family heirloom weapons and then snatching transcripts wasn't the greatest plan. Most of what I've been doing is an act. Throwing up on the airship was part of the plan, I'm not motion sick. Wearing that bunny onesie to sleep was part of the plan. And the Weiss flirting thing also faked. She's a friend to me now. I manipulated Pyrrha into unlocking my aura and it sickens me what I've done. This facade will end but I can't lie to anyone anymore." Tears were in his eyes." I can't be Jaune anymore."
You'll want to tell people who I really am. Or won't want to be around me." Ruby shook her head before replying." Nope. Your my friend and a leader Jaune I couldn't and Ren wouldn't after hearing all of that."
" Whatever you call yourself your my friend and brother in all but blood." Ren stated. " But I only have one question. What do you want to be called?"
" Thad."
Ozpin smiled taking a long drink as he watched from a camera." A Speed Force conduit in my school. Interesting but I recommend some serious changes to Mister Arc's records. Possibly make it Thaddeus Arc Glynda. And we should contact the Arc family soon enough. Along with someone who could create a suitable costume."
Totally unrelated question but what are the guidelines for making a fanfic with song lyrics. Kind of writing a Yj bart allen fic involving warbler songs from glee.