Natalia has a pale countenance more aptly described as expressionless than cold and cruel, enough so to cause others to question her humanity. She wears an inky black long coat, and it doesn't bother her even in a tropical climate inappropriate for such warm clothing. Accustomed to scenes of carnage, it can be said that the smell of death emanates from her entire body.
Natalia is a "money-grubber willing to do anything to make a quick buck" who constantly acts like a wild hedonist unable to save a dollar ahead in her life. Her creed in her line of work is "no matter what method you use, you must ensure your own survival." She somehow becomes the "morally questionable guardian" of the impressionable Kiritsugu, taking on a role he later considers to be that of a mother. She does not treat him like an orphan or adopted child, but rather orders him around like her assistant. She sexually harasses him on numerous occasions, but never goes as far as drinking his semen to obtain prana due to having truly fallen in love with him. It may be only to a small degree, kept locked away as "girlish thoughts" never told to anyone like a "like a good older sister." She is usually a quiet person, rarely talking more than necessary.
Natalia began work as a Freelancer magus with no affiliation to the Mage's Association, making her living by selling them information, taking prey from Enforcers and selling it back to the Association for an inflated price, and as most people in her line of work made money, hunting simple heretical magi rather than "big game" Sealing Designations. She once sought out Odd Borzak, but missed the chance to capture him.
Natalia arrives on Alimango Island after the outbreak of ghouls caused by Shirley drinking Norikata Emiya's potion. Searching out Norikata before the Association and the Church's Executors find him, she inadvertently saves the only other survivor, Kiritsugu Emiya, while fighting some ghouls. Not knowing of the connection, she explains the situation about the vampire extermination to him and asks if he knows of the location of the culprit. Kiritsugu volunteers to kill his father due to the effect that the situation has had on his mindset, claiming that Natalia would have trouble with the Bounded Field. After he kills his father, Natalia appears and claims that the Bounded Field did not take much effort, taking the gun from the stunned Kiritsugu's hand. Even though Norikata could have escaped in the time it took her, she is angry at the fact that a child had to kill his own father even if to prevent future tragedies. Disparaging herself as a bad person, Kiritsugu surprises her by calling her a good person, and she offers to take him off the island and let him decide his course for himself.
She sells Norikata's Magic Crest to the Association, and manages to negotiate to have the lesser parts left for Kiritsugu to inherit. He takes up the same profession as her, acting like an assistant as he is trained in various skill-sets. They spend a number of years together, hunting targets like Heinrich Zepter. Traveling to America, they find the town in which he is located, fighting a number of the villagers that he has under his control before Natalia decides act dead so as to determine his location. Though they manage to slay him, Kiritsugu decides to secretly destroy the recovered Magic Crest so as to keep Zepter's magecraft from being used once again. Natalia later helps Kiritsugu develop his Mystic Code, his Thompson Contender and Origin Bullets, by removing part of his ribs and crafting them into bullets that actualize his Origin.
Their last time together is hunting Odd Borzak after information about him taking Flight A300 from Paris to New York is sent to them. Natalia boards the plane in search of Borzak, while Kiritsugu heads directly to New York to scout out Borzak's identity and companions. Natalia accomplishes her task of finding and neutralizing him without arousing suspicion, but even after disposing of the demonic bees Borzak brought in his luggage, the entire plane is overrun from those stored in his body. All of the passengers and the pilots succumb to them, turning into ghouls, and Natalia can only seal herself in the cockpit to survive. She manages to contact Kiritsugu, relaying the situation and attempting to figure out a solution. The plane is undamaged, and she can manage it well enough from her experience flying Cessna planes with help from the airport's control tower.
The bees and ghouls prove problematic in landing, but she believes they can be handled. Being more talkative than usual, she speaks with Kiritsugu to pass time, recounting the situation, Borzak's evil deeds, and their own dealings in killing magi and Dead Apostles through various battlefields. She explains that she had been troubled over Kiritsugu following the same path as her due to the fact that he has too much potential in killing, displayed by emotionlessly killing his father in a manner that takes others many years to accomplish. She explains that even with such talent, doing what is necessary should not come before doing what the person wishes to accomplish, likening such people to machines. They discuss her upbringing of him, and she likens her role to that of the disciplining normally dealt with by the father that she had at least partly removed from his life.
Although she could only teach him of survival, she feels like they are family, and she becomes embarrassed upon Kiritsugu saying that he sees her like a mother. Deciding to put off such a topic so it won't be awkward for when they meet again, she puts her attention into landing procedures. Kiritsugu only apologizes, knowing that she will not be landing due to him planning on destroying the plane. The bees and ghouls must be completely destroyed lest they be allowed to land and spread the disaster, and Natalia's life cannot compare to the possible loss of life. Natalia mentions that she may have lost her touch, thinking about retirement and being left to only play the part of Kiritsugu's mother. As the plane flies over Kiritsugu, he tells her that she really is his family, and she faintly smiles as the missile hits and destroys the plane.
Natalia is skilled in magecraft, tracking, assassination, the usage of various weapons, and other skills related to her work. Her distant ancestors crossbred with succubi, but that has not granted her any great regenerative abilities or eternal youth. It has given her inhuman reflexes and coordination, and she has the special ability to boost her magical energy stores by consuming semen. She is able to prepare for a mission by taking in that of close magi acquaintances. She also possesses the ability to boost herself by releasing her stores of magical energy at once like a fighter jet increasing its propelling force by fifty percent through its afterburners. Her strength in her limbs, endurance, instantaneous force, and all of her bodily abilities are greatly amplified temporarily. Similar to enhancing a body through runic magecraft, it lasts a much shorter time, so she must compensate through the use of extreme violence on her target by becoming berserk. Only able to keep up an assault for a short period, the price of such strength is that her enormous stockpile of energy gets abruptly cut off. She returns to her normal consumption, returning to her normal physical capabilities.