After the original death of Baron Wolfgang Von Strucker led to his terrorist organization, Hydra, splintering into factions, Cassandra Romulus rose in rank in one such Hydra cell, led by a Supreme Hydra only identified as "Mark." Von Strucker was revived by agents of the Red Skull, and immediately set about rebuilding Hydra, weeding out those who had weakened the organization's reputation and recruiting those he deemed fit to serve. Mark was given intel pointing to a Mayan treasure located in an undisclosed location in South America. He took Romulus and several of his Hydra agents to investigate, presumably hoping to use the treasure to bankroll further activities for his faction. It was a trap, though, and Baron Strucker appeared in person. Mark's men were either cut down or recruited into their attackers' ranks. Romulus was impressed by Von Strucker's cunning, and quickly took advantage of the opportunity to murder Mark and become one of Von Strucker's lieutenants.
Von Strucker was similarly impressed with Romulus' ruthlessness and loyalty to Hydra, and the two became lovers. During "The Von Strucker Gambit" storyline running through several 1991 Marvel annuals, Romulus participated in the baron's competitive tests of loyalty, bringing her into direct conflict with Captain America. Romulus escaped in spite of interference by Dakini, a Hydra assassin.
While her death is never depicted, Romulus has not been utilized by writers since the 1990s. With several leadership changes within Hydra's hierarchy since, some of which have resulted in Baron Strucker being briefly ousted or appearing to be dead, one might infer that she has died off-panel, perhaps displeasing her lover or failing in an undocumented mission. However, her current disposition is ultimately unknown.
Cassandra Romulus possesses superhuman senses, and has proven both a capable hand-to-hand combatant, as well as adept with melee and ranged weapons. As a member of Hydra's upper echelon, Romulus presumably had access to any weaponry available to the organization.