Eric Williams alias the Grim Reaper was a high ranking cybernetic Hydra agent. He was the black sheep of his family. He was a vandal and bully in school, and graduated into petty crime. As he got older, he got bolder by joining the Maggia, an organized crime syndicate. But when petty crime didn't satisfy his destructive urges, he moved on and learned about Hydra. Hydra saw the potential in Eric and outfitted him with a cybernetic arm created by A.I.M. which could turn into a "Power-Scythe" and became a high ranking Hydra officer.
Freeing Baron Strucker
Reaper infiltrates the Vault (Prison) disguised as one of the Hydra agents that S.H.I.E.L.D. had arrested in a plot to spring Baron Strucker from the Vault. He however ends up fighting Nick Fury. After pinning down Fury, the Reaper frees Baron Strucker and gives him his Satan Claw. Both Grim Reaper and Baron Strucker make it to one of the hovercars and take off. After Fury throws Baron Strucker out of the hovercar and towards the S.H.I.E.L.D. Agents, Grim Reaper ends up attacking Nick Fury and is defeated by him when the hovercar explodes. Grim Reaper then ends up remanded to the Vault.
Grim Reaper is among the inmates that escaped from the Vault during a mass-breakout. ]
When Baron Zemo came to reclaim Hydra, Strucker ordered Reaper to fight Zemo, but Zemo easily defeated him.
Some time later, Grim Reaper helps his brother Simon Williams by hooking him up with M.O.D.O.K. who performs an experiment that turns Simon into a being of pure Ionic energy called Wonder Man. He left when M.O.D.O.K. began the experiment.
After that he and Hydra were obtaining Vibranium from the mines in Wakanda until the Avengers foiled their plans. He fled the mines after knocking Klaw in Vibranium, turning him into a pure sound form. 
Grim Reaper spoke with M.O.D.O.K about the Cosmic Cube when Hawkeye attacked them. He escaped, but had a tracer planted on him. Hawkeye, this time with Mockingbird, attacked him again and got captured. When the avengers came to their rescue, his scythe cut cut through by Black Panther's claws. He got knocked out by Captain America's Shield. He was put into custody by Captain America and Black Panther the destruction of Hydra Island.