紅骷髏
As a mercenary, Rumlow enlisted with Albert Malik, the communist Red Skull, in Algeria, serving the Red Skull under the name Frag until he was sent to invade Arnim Zola's Switzerland chateau; Rumlow was ultimately the only team member to survive the assault. There, he also met and impressed, Johann Schmidt, the original Nazi Red Skull, who accepted Brock's services and code-named him as "Crossbones".