Thaddeus Thawne of Earth Prime (Arrowverse.) was created from Nora West-Allen XS and Eobard Thawne the Reverse Flashes DNA. Eobard's send attempt at creating a life for his vendetta. Raised with the hatred of the Allen Family.. From his very first breath he was injected with Velocity Nine and subjected to merciless training. Learning to delay his reaction to pain, and all the most lethal and useful tricks for a speedster. Shown little affection all his life, treated as a project and made to feel belittled very moment his father was around. Growing up with an A.I. he modified as a friend. His connection to the Negative Speed Force not doing his young mind much good.
Gaining some of his father's worst impulses and blond hair, he often shows the twisted part of his family tree. He was made and prepared for one reason, to kill Nora West-Allen. To drive Barry Allen to the breaking point.He has never met her, and has been isolated his entire life. Sent to end her, just as she's bonding with Barry, so that the Flash would be so overcome with rage he would kill Thad.. Of course Thad has no idea about the last part.... All he knows is the mission, the lies he was told.... He doesn't even think of someone acting on their better nature and saving him.
*season 6\7* Redemption
The grandson of Barry Allen worked to make up for his actions, and in his mothers memory. Struggling to adjust to his peers and the coming crisis... As the youngest member of team flash and the newest hero.
Multiverse
Growing up alone in a lab given lessons by the computer Eobard left behind left a confused boy on his way to being a sociopath. Troubled, lost and searching for himself.
(2)
The boy fled his own world after learning the truth, for the reason he was created. wishing to be forgotten by the allens, with no idea of how to follow his father he ran blindly stopping at a earth where no one knew their names. No counterparts, a clean slate for himself. One only he could ruin for himself
3(other dc universes or crossing over to comics.)
The boy who discovered he resided in a restricted universe, a multiverse within a multiverse and escaped it. In world's untouched he'll make his name known