Bree Tanner and Diego were both newborn members of the Seattle newborn army, created by Victoria. They became a couple one week before their battle against the Cullens. They died at different times; Diego was tormented to death by Victoria for discovering that sunlight didn't hurt vampires, like they were told; and Bree was accused of being a criminal and executed by Felix.
- "Diego grinned at me, his face beautiful with light, and suddenly, with a deep lurch in my stomach, I realized that the whole BFF thing was way off the mark. It was just that fast… But even though Diego looked like his normal self again—not made of blazing light anyway—I knew he would never look the same to me. That tingly sensation in the pit of my stomach was still there. I had a feeling it would be there permanently."
- ―Bree on Diego[src]
Bree Tanner lived with her abusive father in Las Vegas, Nevada, for most of her human life. She was led to believe that her mother left her at the tender age of two. In reality, Bree's father had killed her mother. After numerous years of abuse, Bree could no longer endure her father's abuse and ran away from home, completely disregarding his warning of starvation. She barely had enough money to buy a ticket to Seattle; afterwards, Bree was forced to either steal food or eat out of garbage cans. The whole time she worried the police would find her and take her back to her father. Three weeks after deserting her home, Bree encountered Riley. Marveling at his beauty, Bree accepted the "burger" he had offered. It was at this point that Riley brought her to Victoria to be transformed into a vampire.
After her transformation, Bree was brought into the army. While the members fought and killed each other for sports, she sought solitude and tended to keep to herself and hide behind a gifted vampire named Fred, who could avoid unwanted attention with his power. This method kept her alive for the next few months.
- "He ducked close and kissed me—just a peck, but right on the lips. The shock of it zinged through my whole body."
- ―Diego's kiss[src]
Diego grew up in a lower-class, single-parent home in Los Angeles with his mother and little brother. He worked part-time jobs to help out while attending high school, and had a goal in life: to leave his street life and go to college as well as help his brother get a proper education. He managed to stay out of trouble, but when his little brother failed to do so and died as a consequence, Diego tried to avenge him. That night, Diego killed his brother's killer and then was cornered by armed enemies. Just then, Riley Biers came to his rescue and asked if he wanted a new life. Riley escorted Diego to Victoria, who transformed him into a vampire. After a while he befriended a fellow newborn, Bree. The two became fond of one another and became mates. However, Diego learned of information regarding Riley that would have jeopardize the loyalty of the Victoria's army. Because of his knowledge, Riley killed him in an attempt to silence him.
In the next eleven months of his new life as a vampire, Diego acted as the most responsible member, always looking after his lesser tamed mates, even if they didn't want to be looked after. Part of Diego's obedience and loyalty toward Riley came from Riley having been his only friend during Diego's vampiric life. Riley, in return, was very fond of him.
- "I didn't know much about him, just that he was older than most of the others. Riley's right-hand man was the word. That didn't make me like him any more than the other morons."
- ―Bree's first impression of Diego.[src]
Bree was first brought into the army in March, 2006. While Diego and Bree lived together with the army, Bree only knew him from the other newborns' reputation. Everyone believed he was Riley's henchman because he was given such a long-leash when he was really more responsible with his actions than the rest. Diego never noticed Bree because she mostly hid behind Fred, one of the only two gifted vampires in the gathering, to stay out of trouble, especially after one of the newborns tore off her arm and almost burned it.
The Short Second Life of Bree Tanner
- Main article: The Short Second Life of Bree Tanner
During a regular night out, Bree and Diego separated from two other ruthless vampires—Kevin and Casey—who were comparing hunting superhero-style and later fighting for the blood of a victim. The two bonded as they got to know each other, and in the process, fell in love. Bree began to feel safe around Diego because of his generosity, which was unusual in the army. He went as far as to let her feed more than he did.
In the next morning, they hid in an underwater cave and discussed what they knew about the army and vampires. Coming to the conclusion that sunlight and wooden stakes may not be deadly to vampires, Diego and Bree experimented the theory. Bree was hesitant to try, but softened when she saw her hand glitter like diamonds. Coming out of the hole, the two marveled each other's beauty. Diego further encouraged their love by kissing Bree, effectively showing her his genuine feelings. The two then spent the whole day looking for their army. Once they found them, some of the members threatened to finish them off, but Fred prevented from doing so.
Diego planned to tell Riley of their discovery. Bree and Diego followed him to a cabin, where they were confronted by agents of the Volturi. Diego went on to tell Riley, and upon hearing of his discoveries, Riley brought him to Victoria who decided to torment him to extract all information out of him before killing him. To cover his tracks, Riley pretended and informed Bree that Diego was with the one they call "her" (Victoria) when in actuality Diego was tortured by Victoria and Riley before being murdered.
- Main article: Eclipse
When Bree agreed to participate in the army's assault, she had high hopes that Diego would be present; however, to her dismay, Diego wasn't anywhere to be found in the field. It was then she realized Riley and Victoria had killed Diego to silence his words to the newborns regarding the sun. After Victoria's army was completely destroyed, Carlisle Cullen discovered Bree and, out of pity for the child, offered her asylum in exchange for her surrender. Minutes later, the Volturi arrived and interrogated both the Cullen family and Bree. When Jane decided to have Bree executed, the Cullens begged for her life to be spared, going to the extent to take responsibility for her; however, the Volturi refused to accept persuasion and the Cullens were unable to save Bree from her unfortunate death. However, Bree was content to know that her enemies were willing to defend her and didn't try to fight back, as she was too distraught by Diego's death.