Anissa was sent to Earth to inspect what preparations Mark has taken to secure the Earth for viltrumite control. When Mark revealed he had taken no steps towards the domination of Earth, Anissa decides to reason with him instead of using violence. She explains that the Viltrumite empire will bring peace to Earth and share their technology with one another. When reason fails, Anissa resorts to violence and strikes mark down leaving him in a crater. She warns him of another viltrumite agent will return for Mark in the later future and decide his fate, that agent turned out to be Conquest. After her visit to Earth Anissa ran into Allen the Alien, and attacked him. Allen having recently been powered up was having an easy time with her, but when he realized that she would take him to the same prison as Omni-man, he threw the fight. Letting Anissa win and take him to the prison.
Anissa has also been seen during the Viltrumite war, she has fought Mark, Allen the Alien, and Omni-Man near the planet of Viltrum in a last effort to win the war against the Coalition of Planets. After the planet Viltrum was destroyed, Anissa along with the remaining Viltumites relocated to Earth and live amongst it's people in secrecy until the time is right to strike.
Powers and Abilities
Anissa possesses the superhuman abilities of an adult member of the Viltrumite race. These powers include superhuman strength, speed, durability, the ability to fly, a greatly enhanced lung capacity, the power to survive in space unprotected, and has a natural skill for combat (able to go head to head with Allen, Invincible, and even Omni-Man himself).
Anissa Assaults Mark
After the Viltrumites begin to assimilate themselves into Earth culture, they start to repopulate their species as they number less than even 30 Viltrumites now. Unlike numerous males of her species, Anissa sees humans as a species she can simply not breed with and instead chooses Mark because of his strength and genes. Anissa first attempts the 'human' mating habits.
After those attempts fail, she takes Mark by force after he returns from being trapped in a different dimension (Invincible #110). She and Mark battle across the sky when he rejects her advances and strips him, forcing him to mate with her. Anissa was success which resulted in the birth of Markus.