Benjamin was born in Egypt. His mother died when he was very young and he knew nothing of his father. Growing up, he was often passed around to any relative who could provide food or shelter. He was eventually taken into the care of a distant uncle, who used his homeless young nephews and nieces to provide from stealing to street performing.
Benjamin became his uncle's favorite when he discovered his unique gift to manipulate fire and used it for street performances to collect more money. His gift, however, caught the attention of a vampire named Amun, who became so infatuated with his power that he took him away and converted him into a vampire in hopes of utilizing his skill before he could receive attention from the Volturi, who would surely want to add him to their company.
Since then, he became a prominent member of the Egyptian coven, taught the sciences and arts by his creator.
Tia is a distant relative of Benjamin, and had a very large family.
When her mother could no longer provide for her children financially, they were all sent around to other relatives who could. Her singing voice allowed her to stay with her performing uncle, who taught her and her other cousins the arts of street performing and stealing anything to keep them fed and sheltered.
Benjamin and Tia ended up with the same caretaker and became very close to each other.
After Benjamin disappeared without a trace and her uncle died, Tia and everyone else assumed that Benjamin was dead, too. She moved back in with her mother and lived with her for a few years until a clerk for a shipping company offered to marry her. She was eventually married and taken to Suez, and though she did not love her husband, her new home was much more comfortable and she was happier. Meanwhile, Benjamin missed Tia so deeply that he asked for Amun's permission to find her, but he often refused him.
Five years later, he escaped from his hiding place to find her and told her everything that happened. Benjamin was willing to let her live out her life as a human if that was what she wanted. But she decided to become a vampire to be with him - the moment she saw him again, she knew she would be leaving her husband behind to be with him.
They have lived together with Kebi and Amun since then.
They are first introduced in the third part of Breaking Dawn, along with Amun and Kebi. They both decide to be witnesses and to help the Cullens during the Volturi confrontation, against Amun's wishes.
When the situation takes a disastrous turn, Tia touches Benjamin's cheek, as way of saying goodbye. But once the confrontation ended peacefully, they leave Forks to find Kebi and Amun, who left in the middle of the trial.