Brooke was born in Delphi on Caprica and was the youngest of eight children. Her father, Phanto Garner, was killed in a car accident shortly after she was born. Her mother, Maria Garner, had been quite ill following her pregnancy with Brooke and was unable to work leaving the eldest brother, Barry Garner, to be the sole breadwinner in the family. Barry had just joined the Colonial Fleet as an engineer and was away quite often. As such he failed to notice that his younger sister was growing up and he found it difficult to accept it when Brooke started dating.
Brooke was always a mature person for her age and she never let any of her immature boyfriends through high school push her around. This stubborness meant that even her most serious relationships didn't last very long. This fact was lost on Barry who viewed her boyfriends with distaste and saw it as a reflection of her being a poor judge of character.
From a very early age Brooke showed that she had an interest in pursuing a creer in teaching. She was very passionate about the idea and regularly volunteered at youth organizations in her neighbourhood.
Brooke was 20 years old when she met Artimus Bowman in the Delphi public library while he was on shore leave and the two of them immediately hit it off despite the age difference of almost ten years. Artimus felt that Brooke's maturity made up for the age difference but Brooke's family would not see it that way. Barry despised Bowman before he had even met him. During his time in the fleet he had come to loathe arrogant pilots and judged Bowman as being no different. When he refused to give the relationship his blessing her brothers and sisters felt they had to follow suit. Despite this Brooke insisted that they stay as a couple but Artimus felt enormous guilt for the rift that was forming between Brooke and her family feeling that it was his fault. Thus, after almost two years, he decided to end the relationship (and by doing so break Brooke's heart).
Bowman left shortly after to serve aboard the Valkyrie as CAG while Brooke accepted her first teaching job at Wilson Elementary. To her surprise however, less than six months later Artimus showed up at the school and virtually begged for a second chance. Fearing her heart being broken Brooke reluctantly agreed to restart their relationship and this time nothing would stop them. Two years later they were married and their relationship became stronger than ever.
Brooke was quite popular in school but her friendships there didn't last when she went off to Teacher Training College. There she made several professional friendships that would continue onward for much of her career. When Brooke and Artimus restarted their relationship he brought with him the Tolans. Brooke and Emily Tolan immediately became fast friends and later she was introduced to Lacey Tolan. Both Artimus and Brooke saw Lacey in a manner beffitting a niece and she stayed with them several times. Both Brooke and Emily were always on hand to help her with her school work.
Brooke was always passionate about her teaching and more often than not this brought her into conflict with several of her superiors as well as the odd parent. When standards within the classrooms began to fall dramatically it was Brooke who organized the Teacher's strike at Wilson even though she feared for her job as a result.
When the Colonies fell Brooke was in Delphi on Caprica. When news that the bombing had begun she made her way to the Delphi Inter-Colonial Spaceport in an effort to get off world. She managed to secure herself a place on a freighter and escaped only moments before the spaceport was hit. The ship she had boarded eventually found the Battlestar Victorious and a growing fleet of civilian ships including the Olympica. After several months she discovered that both Scott Tolan and Emily Tolan had survived along with their three children and she quickly made efforts to contact them. It was especially clear to Emily that Brooke had been traumatized by the events in Delphi but she wouldn't open up about them for quite some time.
Although she has no evidence to support it she firmly believes that her husband is alive somewhere.