as a result of civil war and the government needing people to take down unregistered supes, Norman Osborne (the Green Goblin) takes over the Thunderbolts (which is like the Marvel Suicide Squad) in an amazing Ellis run and are straight up super villains loving the chance to beat the shit out of superheroes on the government payroll.
As a result of Secret Invasion, where all Starktech gets Skrull infiltrated, only Osborne tech is still working, and he kills the Queen Skrull live on TV.
So they give Norman Osborne control of S.H.I.E.L.D, which he renames H.A.M.M.E.R, and then he makes his own Avengers, with hookers and blackjack, who are all straight up super villains just dressed up as 'real' Avengers - Venom is Spidey, Bullseye is Hawkeye, Moonstone is Ms Marvel, Osborne wears his own knock off Iron Man armour with a stars and stripes paintjob and calls himself IRON PATRIOT
etc
And mostly gets away with it, cashing goverment paychecks, covering up all the super villain shit the team get up to so the public don't realise its different people in the costumes etc.
it is WAY FUCKING BETTER than it ever deserved to be