Korra was the Avatar from the southern water tribe, reincarnation of the Airbender Aang. She was first and foremost a Waterbender. When Tenzin visited the south pole to tell her that she would have to wait for him to teach her, she followed him back to Republic City. She found the city in disarray, and wanted to help restore it to the dream city that the Avatar before her had envisioned.
While she tried her hardest to learn Airbending, the element most opposite to her own hard-charging personality, it wouldn't come to her. In her frustration one night, she went against Tenzin's direct orders to remain on Air Temple Island in favor of visiting the Pro-bending Arena, home of her favorite sport. There she met the Fire-ferrets, and watched them dominate their competition. She went again for their next match, to find out that their Waterbender had bailed on them. She stepped in and saved them from having to forfeit, and while she had a rough start, she quickly got the hang of it.
In her short time there, she discovered an organization of non-benders calling themselves the Equalists, led by a masked man called Amon. They hated all benders, insisting that they used their power to oppress them. While some people, such as councilman Tarrlok, did indeed abuse their power, they couldn't understand that those people were few. Korra did her absolute best to fight against the Equalists, and even had to sneak into an Equalist rally to save one of her teammates from Amon, who claimed to have the power to permanently take away a person's bending. Korra didn't believe it, until she saw it happen.
And still she fought. She was brave and strong and loyal to a fault. She cared about every single person, and always wanted to help others. Sometimes her pride got in her way, and she stumbled, but she always picked herself up, dusted herself off, and tried to make things right. She wore her heart on her sleeve, never holding back how she felt or what she thought. Korra refused to ignore her instincts, and her instincts always told her that she needed to be truthful. She captured the hearts of benders and non-benders alike, and quickly gained the attention of both of her male teammates.
Her teammates were her first human friends, after the polar bear-dog Naga, and she spoke of them as being the very best friends she could have asked for. They didn't want to mess up their friendship, or their Pro-bending team, but both brothers had been captured unintentionally by her natural, if a bit raw, allure.