An extremely attractive young woman, daughter to Gerald. She hates being on Lalonde and is highly rebellious against her father. She engages in frequent sexual intercourse any way she can and is especially fond of threesomes, as long as she’s the only female. Upon arriving at Aberdale and the savanna region beyond the settlement, he learns rather quickly that she hates living in the grassland in particular and on Lalonde in general. She turns 18, but everyone is too busy forging their new lives to remember her birthday. This proves to be the last straw and, as she is now legally an adult, she simply ups and leaves the settlement, hitching a ride downriver on the Coogan. Ultimately, she becomes the victim of the Gail and Len Buchannan, the merchants of the Coogan.
Marie's highly sensuous body becomes strong and more muscular while she journeys on the Coogan back toward Durringham. Her attractiveness is greatly enhanced. As the merchant ship nears the capital, she takes a few belongs she has secretly accumulated from bartering on the trip and abandons the ship. Len and Gail Buchannan both object, for different reasons. Gail, because Marie is essential a work slave that entertains her as she watch Marie and Len during sex. Len wants her to stay because she is so attractive. Marie is completely unmoved by this. She has no feeling for anything or anyone at this stage in her life, only the joy of leaving the ship and being, for the first time since arriving on Lalonde, truly free from everyone and on her own.
After finally making it back to Durringham, she finds employment in the Commercial Office, where she quickly catches on to the ins and outs of the cities economics. When Joshua arrives she sees this as an opportunity to negotiate her way into being the middleman on his mayope deal. She talks him into letting her secure the mayope he is seeking at a lower price. She ends up running in to Dexter Quinn (who has apparently made it to Durringham by stealing one of Laton’s landcruisers). She discovers that he wants off the planet and offers to introduce him to the Lady MacBeth for possible passage. She will do this for a finder’s fee, of course. Quinn agrees and, in the meantime, negotiates his way into having sex with the beautiful Marie.
In being exposed to Quinn, Kiera Salter, who takes full advantage of Marie’s beautiful body in spreading the possession of others, possesses her. She ends up leaving Lalonde, along with Laton, on the Yaku and traveling to Valsik. There, she seduces Horgan to come to bed with her. There he is tortured by Marie (Kiera) and three other possessors as Dariat takes poison and kills himself, so that he can enter Horgan’s body as a possessor, complete with all their powers and with full intent of reeking revenge upon Rubra.
She gets into an argument with Dariat in Tacoul Tavern over the purpose of their possessed group. She emerges as clearly in charge and possesses everyone in the tavern.
Quickly possession spreads through Valisk. Soon, Kiera is in control of the entire length of Valisk, though many non-possessed pockets remain. All total, about 900,000 people are possessed on Valisk. Not enough to take the habitat out of the universe. She plans to entice several million additional souls to the habitat for possession. That will serve two purposes. First, it will be enough to take the habitat out of the universe. Second, it will provide enough of a population to keep the society "alive and fresh" after the transfer. This second point is especially important to Kiera because, as she puts it, "the purpose of life is to experience. Experience whatever you can for as long as you can." With eternity facing them, a large population is essential from her point of view to make continued existence acceptable.
She makes a sensuous sensevised recording that is distributed throughout the nearby stellar systems tempting people (primarily teenagers and young adults) to come to Valisk. “Now we live as we please,” she tells her audience of millions. “Valisk has become a place where every wish is granted, however small, however grand.” She tells everyone she is going to take Valisk out of the universe to a place where everyone will have “energistic power.” She entices teenagers from other worlds to come along for the voyage. 15 hellhawks dispatch her sensevised message across the Oshanko sector of the Confederation with great effect. Deadnights begin flocking to Valisk any way they can.
She is approached by a representative of the Capone organization with a proposition to obtain antimatter from the organization in exchange for a fleet of hellhawks. She is told that with the antimatter she can blast the nearby planet Sprinager’s SD network, possess the planet and get off her decaying habitat. She promises she can let the organization have “about 70” hellhawks, but wants to go to New California personally to cut the deal with Capone.