Sorreltail is a tortoiseshell-and-white she-cat with amber eyes and a white chest and paws.
- Sorrelkit is born in the ThunderClan nursery with her littermates Rainkit and Sootkit.
- When she and her littermates are caught in the fire, Mousefur, Longtail, and Fireheart help bring them across the river to RiverClan territory, where they are treated by Mudfur.
- She is the most active and adventurous of the litter.
- She is seen playing with Bramblekit and Tawnykit. Bramblekit accidently bowls her over, but she jumps back up and continues to play.
- She follows Darkstripe out of the camp and sees him talking to Blackfoot. Darkstripe discovers her and tricks her into eating deathberries. Graystripe sees and attacks Darkstripe.
- Cinderpelt feeds Sorreltail yarrow and she soon recovers and tells Firestar what happened. Darkstripe is then exiled.
- When BloodClan attacks, Sandstorm is in charge of teaching the kits battle moves so they will be able to defend themselves.
- Sorrelkit and her littermates fight over who gets to be Sandstorm's apprentice. Sandstorm hints to Firestar that she would like Sorrelkit as an apprentice and Firestar promises her to her.
- Sorrelpaw gets apprenticed sometime between The Darkest Hour and Firestar's Quest. Her mentor is Sandstorm.
- Sorrelpaw is seen running into Cinderpelt's den, wailing about a thorn in her paw. Cinderpelt scolds her for making such a fuss about just a thorn.
- Sorrelpaw's mother, Willowpelt, gets killed by a badger and it affects Sorrelpaw greatly. She and her brothers stay in the nursery for a while to recover.
- When Sandstorm leaves with Firestar, Dustpelt becomes her temporary mentor.
- In between Firestar's Quest and Midnight, Sorrelpaw gets hit by a monster on the Thunderpath. She stays in Cinderpelt's den for three moons and her warrior ceremony is delayed. Her brothers have already received their warrior names.
- Before the ceremony, she jumps on Brambleclaw excitedly, waking him up. He teases her about acting like a kit and not a warrior.
- Sorrelpaw becomes a warrior in Midnight and her warrior name is Sorreltail.
- It is revealed that she is very close to Leafpaw, due to being confined in the medicine den for three moons.
- She accompanies Leafpaw to the RiverClan border to gather celadine. They see WindClan cats still drinking from the river, and Sorreltail notes that they shouldn't be.
- The two of them talk to Mistyfoot and she tells them that cats have disappeared from RiverClan as well.
- After finding out that Twolegs have been destroying the forest, she goes with Leafpaw to WindClan. They get attacked by WindClan warrior and are chased into RiverClan territory where they are rescued by Mothwing. Mothwing invites them to stay and Sorreltail states that she is careless about the warrior code due to her mother being a rogue.
- Sorreltail later goes with Leafpaw to investigate the Twolegs. She watches as Leafpaw gets caught in the trap but cannot do anything to stop it.
- When Squirrelpaw and Brambleclaw return, she helps Squirrelpaw rescue Leafpaw from the Twolegs.
- She seemed to be jealous of Cody for spending so much time with Leafpaw and is happy when she leaves, although she doesn't let Leafpaw know.
- Sorreltail almost falls off a cliff during the Great Journey, but Leafpaw saves her.
- She later tries to hunt a mouse, despite Brambleclaw's instructions not to and falls down a steep slope. Brambleclaw later scolds her for not listening.
- In the new territory, she finds Leafpaw hiding in a holly bush and confides to her that she is having Brackenfur's kits.
- When Daisy arrives, Sorreltail is very interested in her kits.
- Sorreltail begins kitting during the badger attack. Cinderpelt comes into the nursery to help her. A badger breaks in and Cinderpelt is killed in an attempt to protect Sorreltail. Leafpool comes in and says her last goodbyes to Cinderpelt and then helps Sorreltail kit.
- She gives birth to four kits, and Leafpool reports to Brackenfur that they are all healthy.
- Sootfur dies in the badger attack and Rainwhisker is anxious to bring the news to Sorreltail. Sorreltail gest very distressed but is comforted by Brackenfur.
- Sorreltail names her kits Molekit, Poppykit, Honeykit, and Cinderkit. Molekit is the only tom, Poppykit is said to look exactly like Sorreltail, and Cinderkit is said to look like Cinderpelt, although this changes later. Cinderkit is named in honor of Cinderpelt.
- Leafpool sadly reminisces about all the good times they had back in the old forest, and notes that it will never be the same again since Sorreltail is a mother and Leafpool is a medicine cat.