At AIM’s instructions, Protocide attacks and nearly kills Captain America. They get him to hate Cap by telling him that he was supposed to be the big hero, but Captain America stepped in and knocked him out of the running, relegating him to becoming Protocide.
AIM needs Cap out of the way so that they can take over SHIELD.
A SHIELD field team stops Protocide before he can kill Cap, and Protocide wipes the floor with them as well.
While Cap is healing from the battle, he researches Protocide and learns, from the imprisoned living supercomputer Cache (who has read the entire internet) that Prtocide was an early Project: Rebirth test subject–but the pain of the early serum made him insane.
Cache also escapes from prison soon after the visit–by hologramming himself to look like Captain America.
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