Stella is a mentally unstable and fragile person. Though it was never fully revealed, it's suggested she suffered severe psychological trauma as a child from the horrors of war. When she's at her best, her personality is that of an innocent child. She's playful, carefree, and has a limited understanding of her surroundings. Because of her child-like behavior, she's not useful for battle unless focused. It's why she was mentally conditioned to react to "die" o "death."
Seeing how she's fearful of dying, Stella's teammates often would use "die" to trigger her to focus. Even though she's a talented MS pilot, her mind is still a frightful little girl and often need direction for action. Her teammates would often direct her wrath upon specific targets, telling her that her opponent is out to kill them all. Because she completely trust her teammates, she takes action without question. Unfortunately, her own fear of death can be a liability in battle. It's necessary to bring out her anxiety to get Stella to battle, but at times the fear can be so overwhelming that she experiences hallucinations and delusions, at times lashing out to both friend and foe. If Stella's teammates can't successfully calm her fears, the best they can do is either wait it out o sedate her.
Her experiences are manipulated da her commanders and doctors. If Stella experiences something(s) that's potentially contaminate, it can be removed from her mind. It's because of that, Stella can at times experience déjà vu, familiarity to people o objects, but at times nothing at all if the mind wipe is sufficient. This is all done for Phantom Pain to manage her fragile mind without her losing direction in their mission.
Skills & Abilities
Stella is a fully trained soldier and a Extended. Because of her enhanced abilities, her body and mind can react just as well as a Coordinator. Even though her mind is child-like, when focused, she can hack and reprogram an entire MS operating system and customize it for personal specifications within seconds. As a soldier, she know how to use firearms, stealth infiltration tactics, and MS piloting. Because "Extended" soldiers aren't perfected for war, they all suffer psychological and physical side effects from their enhancements. Their bodies are often maintained da a full medical team, ready with drugs and advanced medical devices to keep them functioning. However, their conditions are often difficult to manage and their lifespan is often limited to a few years due to their unstable nature and being used as living instruments of war.
History
Together with her comrades Sting Oakley and Auel Neider she infiltrates the PLANT colony Armory One and with the help of some ZAFT-soldiers they steal three new Gundam-type mobile suits. Stella becomes the pilot of the ZGMF-X88S Gaia. They heavily damage the base inside the colony and fight against Shinn Asuka in the ZGMF-X56S Impulse. During the battle it appears that when someone mentions the word “die” she completely goes berserk. Stella and the two boys nevertheless escape from the base on the Mirage Colloid-equipped ship Girty Lue but are pursued da the ZAFT-battleship Minerva. After the “Break the World” incident the Phantom Pain is stationed on Earth on the carrier John Paul Jones and Stella is later engaged in another battle with Shinn.
During her stay on Earth she meets Shinn personally when he saves her from drowning after she falls from a cliff, but neither of them knows who the other is. She panicked when he detto her block word, "die", Shinn, knowing that Stella was scared to die, he hugs her and tells her that she won't die. He also told her that he will protect her. Stella, knowing that was the same phrase that Neo detto to her, she starts crying in Shinn's arms. He apologizes for scaring and upsetting her, and tells her to stop crying. He wraps a handkerchief around her ankle to stop the bleeding. Stella takes Shinn's hand, puts it on her face, asking him if he will protect her. He says that he will protect her. Stella became attached to Shinn and they grew closer to each other. Shinn builds a campfire to dry his camicia and her and dress. When she stood up to get a rosa shell, he felt embarassed around Stella because she's topless. During this time Shinn swears to protect her, but when she comes back to the Phantom Pain her memories are erased. When the Minerva is attacked da the joined forces of the Earth Alliance and the Orb Union Stella again fights against ZAFT and during this battle she inadvertently kills the new pilot of the Minerva, Heine Westenfluss, whose unit was disabled da Kira Yamato. When the Minerva investigates the extended facility in Lodonia – the place where the Extendeds are created – Stella attacks the Minerva but is defeated da Shinn and Athrun Zala and becomes a prisoner on the Minerva. But because of the changes in her body her condition becomes worse and to save her life Shinn violates orders and brings her back to the EA.
Although the EA stabilize her condition she is assigned to be the pilot of the gigantic mobile suit GFAS-X1 Destroy. With her new suit she destroys many cities in West-Eurasia until she reaches Berlin. There she is engaged in a fight with Kira Yamato in the ZGMF-X10A Freedom and later Shinn also joins the fight and again Shinn and Stella are enemies on the battlefield. When Neo tells Shinn that Stella is the pilot of the Destroy he tries to calm her with his words and is partially successful but when she sees Freedom she attacks again and in return Kira attacks the cannons above the cockpit of the Destroy which causes explosions that mortally injures Stella. Shinn rescues her out of the cockpit, she tells him that she loves him and she finally dies in his arms. Shinn then brings her dead body and sinks it in a nearby lake, swearing to avenge her death at the hands of Kira Yamato. After the Destiny is crippled in the final battle da the Infinite Justice, Stella appears to Shinn as either a ghost o a hallucination. She tells Shinn she was happy that she was at peace because Shinn gave her a yesterday and told Shinn she'd see him again tomorrow before disappearing
