Hazelkit was born to their parent Ryewhisker, the long-time medicine cat, and their father Bearshade. She had two siblings, a sister named Birdkit and a brother named Acornkit. Hazelkit was born with a disfigured back leg that her parents believed would set her back for moons as she learned how to live with the disability.

But from day one, Hazelkit wouldn't let it slow her down, especially after her siblings started playing and wandering around. She was determined to follow them anywhere. But the leader at the time, Badgerstar, was being heavily influenced by his deputy Weaselpelt, who had a personal grudge against Bearshade and soon his kits. But he honed in on Hazelkit in particular.

While Hazelkit was training, preparing to become an apprentice and ready to learn what the world was like, Weaselpelt was whispering secrets and rumors to Badgerstar.

Things changed when Hazelkit became Hazelpaw. She was looked at as a "special case" and was allowed to be mentored by her own father Bearshade. This allowed the two of them to get rather close over the years. But Hazelpaw was constantly bullied by Weaselpelt's own apprentice who was older than her by only a few moons, Nettlepaw. 

Nettlepaw bullied her, always pointing out that she could never be as good of a warrior as everyone else because of her leg. But Hazelpaw ignored him, and instead focused on becoming better. She realized she had an unfair disadvantage pushed against her but she would not let it dominate her life. She would be a good warrior just like everyone else was, especially her father Bearshade.

Nettlepaw became Nettlebite and joined his former mentor in a plan that would soon nearly ruin Hazelpaw's life.

As Badgerstar started getting older and more senile, it was anticipated that Weaselpelt would take over soon. And as Nettlebite and Weaselpelt fed Brindleleaf and Ryewhisker hints of a disastrous prophecy that would be spearheaded by Ryewhisker's own daughter Hazelpaw, things began to drastically change.

Badgerstar was convinced that Hazelpaw would cause nothing but trouble. So when the day came that her name was changed to Lostleg, right in front of her whole clan, everyone was shocked. And only a few days later, Nettlebite and Weaselpelt accused Lostleg of poisoning his prey with hazelnuts. Badgerstar was not merciful as he forbade Lostleg from ever returning to her clan. He said that she wasn't fit to be a proper warrior from the beginning and he should have kicked her out a long time ago.

Her family did not believe the accusation though and snuck her prey and medicine when she needed it. But Lostleg would not back down. She knew that Nettlebite was full of lies, and Weaselpelt was worse and was trying to steal the leadership. So with the help of her brother Acornnose, sister Birdbelly, and her always loving father Bearshade, they worked to bring Weaselpelt to justice. It came down to a battle in the camp that ended Weaselpelt's life, and soon after Badgerstar, as Lostleg brought them to justice using her claws. Nettlebite ran off into the woods, deciding his life was worth more than this futile attempt to become the leader.

Lostleg was appointed the new deputy after the deaths of Weaselpelt and Badgerstar. She went on to reclaim the insulting title that Badgerstar had given her and resumed her life as Loststar, the newest leader of GladeClan.