Banjo originally was not meant to be a main character despite his initial popularity. Instead, he was meant to be a small-time character in a game Rare was developing for the SNES, codenamed Project Dream. However, the game was taking much longer to develop than originally anticipated, and development was moved to the Nintendo 64. But after Super Mario 64's release and immense success, Rare realized the game needed major overhauling. Instead of redeveloping the game, they opted to cancel the project and make Banjo the main character of his own game. Banjo, Kazooie, Tooty (named Piccolo in Project Dream), Grunty (a giant in Project Dream), Tiptup and Captain Blackbeard (appears in Banjo-Tooie) were all meant to be minor characters in Project Dream, but were brought along to Banjo-Kazooie.
The first significant event in Banjo's life occurred when he met Kazooie. The two quickly became best friends and decided to live together, along with Banjo's sister, Tooty, in Spiral Mountain. He was content with his life, but Kazooie and Tootie constantly bugged Banjo to embark on an adventure someday.
Diddy Kong Racing
Banjo originally debuted in Rare's 1997 racing game Diddy Kong Racing, along with future Banjo-Kazooie character Tiptup. In Diddy Kong Racing, Banjo received a call from Timber asking Banjo if he could help drive Wizpig off Timber's Island. Banjo accepted, though he didn't feel racing was something he was particularly interested in. Kazooie did not appear in Diddy Kong Racing.
One year after helping Timber drive Wizpig off, Banjo decided it was time to take Kazooie and Tooty's advice and go on an adventure in the bear and bird's first solo adventure, Banjo-Kazooie. Unfortunately, the day before Banjo and Kazooie were to leave, Gruntilda kidnapped Tooty for her beauty, forcing Banjo and Kazooie to save her. So, using teamwork and a series of moves taught by Banjo's neighbor, Bottles, the two team up to defeat Grunty and save Tooty.
Banjo-Kazooie: Grunty's Revenge
Banjo Kazooie: Grunty's Revenge takes place two months after Banjo and Kazooie. After originally defeating Grunty, her minion, Klungo, transferred Grunty's spirit into a time machine, which the witch then used to travel back in time to ensure Banjo and Kazooie never met. But with the help of Mumbo Jumbo, Banjo was able to rescue his friend and defeat Gruntilda for a second time.
Two years after defeating Grunty for a second time, Gruntilda's sisters found her skeleton, ending the two years of peace in Spiral Mountain. Gruntilda then blows Banjo's house up, killing Bottles and forcing the two to stop the witch before she can use all of the energy in the world to rebuild her body and hopefully revive both Bottles and the Jingo King. With Bottles' brother Jamjar's help, Banjo learned to survive without Kazooie in his backpack, and to use her as a gun, which was the key in defeating the witch for the third time.
Banjo-Kazooie: Nuts & Bolts
With Gruntilda out of the way, Banjo decided to fix up his house and finally settle down for a peaceful life. However, he stopped halfway through the rebuilding process, instead opting to eat pizza and play video games all day, making both him and Kazooie obese. Eventually Grunty came back again, followed by a mysterious being called L.O.G. (Lord of Games). L.O.G. set up a competition between the duo and the witch to see who would own Spiral Mountain, but with Grunty being only a skull and the bear and bird extremely overweight, L.O.G. gave Gruntilda a mechanical body and made Banjo and Kazooie fit again to see who would win. After a grueling test of vehicular combat, Banjo won the deeds to Spiral Mountain, while Gruntilda was forced to work in L.O.G.'s factory for the rest of her life (though she vowed she would make a new game with L.O.G.'s technology).
Sonic & Sega All Stars Racing
In 2010, after two years of enjoying retirement, Banjo heard of a new racing tournament. After the events of Nuts & Bolts, Banjo was interested in entering another racing tournament and decided to fix up the "Bolt Bucket" he used in Diddy Kong Racing and race with Sonic and others.
Banjo is much more timid than Kazooie. The bear is a very well-mannered easy going guy. He is very polite and uses "Mr." and "Mrs." when speaking and enjoys helping both friends and strangers out. But, while he does mean well, he comes off as a bit slow to many, often trying to say something witty but instead just appearing awkward. He can be very brave at times, rushing into situations without thinking all the way through. For the most part, he is very timid, often nervous about committing to a plan or situation. Despite his bravery, he always mentions how he would rather sit down and eat honey and nap, making him come off as extremely lazy to those around him.