Ramsey Rosso was a scientist that has Hemophilia, because he couldn't risk himself he tried to find a cure, so Ramsey tried to change blood, so instead of helping humans age, it would preserve them and make them invulnerable and immortal. After injecting himself with the new blood that he had created, Ramsey gained invulnerability and the ability to control blood. A secret he would keep for years on end.
Although successful in his experiments Ramsey wanted to continue his research, so he stole blood samples from the Central City Police Department. Continually tinkering with the various metahuman blood samples procured from all of the precincts DOA patients within the morgue; this allowed him to refine his unique abilities both through biochemical means and outright practice in their use. When the missing evidence came to the attention of Central Cities finest, Director Singe had Allen and his new partner; Kristen Kramer, look into it.
Fearful of discovery, Ramsey went about using his abilities to terminate any leads that could reveal his involvement. When Barry discovered someone had set fire to the evidence room pertaining to the case, he also found a number of officers debilitated by Ramsey. Who'd also worked his abilities on him to cover his tracks.
Now aware that he'd been discovered. Rasso moved to dispose of all the blood samples he'd stolen before someone finally caught up with him. Soon after, Barry Allen as the Flash figured out he was behind the caper and caught him in the act. But the coroner fought back with his test given powers, incapacitating Flash the same way he put out the workers within the file room as he explained his motives while showing off his power. After an emotional outburst by The Flash put him on the ground hard, he picked himself up and dusted off now amazed at the kind of power and resilience he now Possessed.
Now more than fearful of The Flash's negativity power as their destructive qualities hurt more than they saved, he prepped. His powers transformed him as he prepared to battle The Flash, in continence of how most of the gem cities rogues name themselves after their fashion. He gave himself a new name... Bloodwork.
Ramsey's tampering with metahuman blood to cure his hemophilia had altered his genetic structure. He now has the ability to change, generate and alternate his own blood at an accelerated rate.