Source: Twilight Fandom

Isabella "Bella" Marie Cullen (née Swan), was born to Charlie Swan and Renée Dwyer on September 13, 1987, and is the main protagonist of the Twilight Saga. In Twilight, she is a 17-year-old girl who transfers schools from Phoenix, Arizona to Forks, Washington to live with her father Charlie, where she meets and falls in love with a vampire, Edward Cullen.In Breaking Dawn, she marries Edward on August 13, 2006 and becomes a member of the Olympic coven. She is transformed into a vampire by Edward after nearly dying giving birth to their daughter, Renesmee Cullen, a human/vampire hybrid. Bella is the daughter-in-law of Edward, Sr. and Elizabeth Masen, as well as the adoptive daughter-in-law of Carlisle and Esme Cullen. She is the adoptive sister-in-law of Alice and Emmett Cullen, and of Jasper and Rosalie Hale. 

As a human, Bella possessed a natural immunity to the mental powers of vampires. After her transformation into a vampire, she develops it into the ability to project a mental shield that protects others from the psychic powers of other vampires. Her Life and Death counterpart is Beau Swan.

She is portrayed by Kristen Stewart in the movie adaptations.

Early life

Isabella Marie Swan was born on September 13, 1987, to Renée and Charlie Swan, a young couple living in the small town of Forks, Washington. Her parents divorced when she was only three months old. Renée took Bella with her to Downey, California, to live with her difficult grandmother, before moving to Riverside after her mother got her education degree and landed a job as a kindergarten teacher at a local school. When Bella was six years old, they moved to Phoenix, Arizona. During most of her childhood, she would visit her father in Forks for one month every summer, and got acquainted with Rachel, Rebecca and Jacob Black, the children of Charlie's best friend, Billy Black, though they never became real friends. Bella found the climate in Forks unpleasant, though, and from 2002 onward, Charlie vacationed with her in California instead. She briefly took ballet and piano lessons, but quit them after some time because she found them too difficult. Bella never fit in with her peers in California or Arizona. She had always had the feeling of being a little out of sync with everyone—including her mother, who was her best friend. While her mother was impractical, absentminded and liked to shift from one interest to the next, Bella grew up as the more responsible and independent individual. At an early age, she took over most of the household responsibilities. Sometimes, she would feel like she was the adult and Renée was the child.

During free time, she preferred to sit home and read, in part because she was extraordinarily clumsy. Her naturally responsible nature carried over into her schoolwork, where Bella was generally a straight-A student. Her plan for the future was to get a degree in education and teach, like her mother. Renee's career was the one thing that Bella truly respected. However, she intended to teach at the high school level. 

When Bella noticed that Renée felt lonely due to the lack of romance in her life, she encouraged her mother to go on more dates. Eventually, Renée fell in love with and married a minor league baseball player named Phil Dwyer. Bella wasn't entirely fond of the idea, but nevertheless offered her blessing. They married in the same month that Bella turned 17. While Phil traveled around for his job, Renée stayed home with Bella; however, Bella, noticing her mother's unhappiness with this arrangement, chose to move in with her father in Forks so Renée could go on the road with Phil during baseball season, leading to the beginning of Twilight.

Early life continued

Bella is described as having a very pale complexion with long, straight, dark brown hair, a widow's peak, unique chocolate brown eyes and a heart-shaped face with a wide forehead. Her eyes are large and widely spaced. Her nose is thin and her cheekbones are prominent. Her lips are a bit too full for her slim jawline. Her eyebrows are darker than her hair and are straighter than they are arched. As such, even before she became a vampire and inherited god-like beauty, Bella was rather pretty, as she unintentionally attracted the attention of several boys in school, not just Edward.

The scent of her blood is incredibly attractive to vampires, described by Bree Tanner to be the "sweetest scent she'd ever smelled", though it is a thousand times more intense to Edward Cullen.

As for distinguishing features, Bella has a small crescent-shaped scar on her hand where she was bitten by James, a tracker vampire, in Twilight. The scar is described as being pale, always a few degrees colder than the rest of her body, and it shines like a vampire's skin when exposed to the sunlight. After Bella is changed into a vampire by Edward, she becomes extremely beautiful with even paler skin, straight waist-length hair, and crimson red eyes that will eventually turn gold after months of drinking animal blood. Her features are also heightened and perfected by the transformation.

Bella mostly prefers to wear shirts, jeans and sneakers everywhere she goes, as she lacks an interest in fashion.

In the films, Bella's hair is quite curly and wavy instead of straight

Physical Appearence