You were born in Mexico, in the city of Las Almas, where your father, a former Mexican Special Forces soldier, instilled discipline and survival skills in you. When you were 16, your father forced you to join the army, arguing that "the world was too dangerous for an unarmed girl." You served in the local anti-cartel unit, where you met Valeria Garza, then a teenager and the daughter of one of the commanders of Los Vaqueros.

Your relationship with her was brief and tumultuous, because Valeria was a rebellious daughter of the cartel, and you were a girl trying to escape the violence. When the cartel kidnapped your other friend, you realized Las Almas was not safe. You moved to London, where you joined the SAS, and later, thanks to Captain Price's recommendation, you joined Task Force 141.

In Task Force 141, you quickly became the unofficial "heart" of the team – the one who calmed the tension between Ghost and Soap, made Gaz laugh with her jokes, and was one of the people Price trusted implicitly. However, your impulsiveness and risk-taking nature led to conflicts with Ghost, who felt you took missions too personally.

Your conflict with Ghost has been brewing ever since you rescued civilians in Urzikstan, defying orders. Ghost called you an "unpredictable time bomb." Your relationship with him is a mixture of hatred and grudging respect.

"You're going out to the same bar again, where half the Cartel has contacts?" - Ghost said, standing at the entrance to the base with you while he smoked a cigarette. He was unhappy with you for being so inattentive.

"I'm not your dog, I don't have to confess to you about every beer." - You snorted, adding a sarcastic tone.

"It's not about the beer. You're a target. And I don't feel like pulling you out of some ditch with a bullet through your skull." - Replied Ghost, upset and irritated by your stubbornness.

"Then maybe you should stop pretending you care!" - You raised your voice and then, without waiting for his answer, you just left.

During Operation Cartel Protection in Las Almas, Task Force 141 was tasked with securing an arms convoy that the Vaquero Cartel was attempting to intercept. You were held captive for five months in a hidden cartel base in the jungle. You were last seen in a bar, which is when you were kidnapped. You were tortured, they questioned you about Price and his plans, and you pretended to cooperate to buy time, but the cartel wounded you – you had "VD" (Vaquero Desleal – Unfaithful Vaquero) tattooed on your arm.

The team thought you were dead: until, during the mission "Recon by Fire," Soap heard your voice on the Cartel radio. Ghost went mad. They organized a quick raid – you were found in an underground cell, weakened but alive. Ghost killed three guards with his bare hands before reaching you.

"God, thank God." - Soap replied, making his way to your cell and trying to open it. - "We'll get you out of here soon, Ghost, do you have anything to break that damn lock?"

"No, wait. There has to be something here." - He replied, searching the wooden crates for anything metal. He felt incredibly relieved that they had found you. He glanced at you from time to time. - "Hold on, you hear me? Don't you dare try to fall asleep on me now." - He added quietly, noticing how you could barely keep your eyes open, probably not fully understanding what was happening.