Sagefern

Kithood

Sagekit was born in RiverClan to Warmmoss and Mintfrost alongside her brother, Pebblestep. She took an interest in the ways of a medicine cat and couldn't seem to stay away from the medicine den. Otterpelt spoke highly of her at a Moonstone meeting. (Shadows of Blood, chapter 7)

At a gathering, Frostedstar announces that Otterpelt expects that she will have an apprentice soon, as one of their kits has taken an interest in the ways of a medicine cat. Hawkfeather asks Otterpelt if it's Sagekit, and she warmly confirms it is, and she can't keep her away from the medicine den any longer. (Shadows of Blood, chapter 7)

Apprenticeship

Sagepaw started her apprenticeship under Otterpelt, becoming the medicine cat apprentice of RiverClan.  (Shadows of Blood, allegiance update 5)

Sagepaw is nervous at her first Moonstone meeting. Otterpelt purrs as she introduces her new apprentice to the other medicine cats. Seeing her discomfort, she gently adds that these cats are all friendly. Sagepaw nervously greets them, slowly straightening. Starfaith and Dewstorm greet her warmly, and Sagepaw ducks her head shyly. Inside the cave, Sagepaw is in awe at the sight of the Moonstone. Otterpelt holds her medicine cat apprentice ceremony, presenting her to StarClan. She then instructs Sagepaw to touch her nose to the Moonstone, and she dreams with StarClan. Afterwards, Sagepaw excitedly tells Otterpelt about her first meeting with StarClan. When they notice Starfaith in distress, they hurry over. They leave the cave with the others while Dewstorm and Starfaith stay behind a while. (Starfaith's Fate, chapter 14)

Moonstone Attack

Planning to eliminate the medicine cats, Deserve sends Bloodfur, Mottledface, and a group of his soldiers to attack the medicine cats during their Moonstone meeting. Sagepaw awakes as they are attacked and sees Mottledface smother Otterpelt. She crouches over her mentor, shrieking at her to get up, then wails in grief.  (Shadows of Blood, chapter 22)

Sagepaw, Ryeheart, and Spicewhisker struggle to fight off the soldiers blocking the tunnel exit. Ryeheart and Spicewhisker hold off the soldiers while Sagepaw, Dewstorm, and Creamheart escape.  (Shadows of Blood, chapter 22)

Sole Medicine Cat

After Otterpelt's dead, Frostedstar gives Sagepaw her full name, Sagefern, and makes her sole medicine cat of RiverClan. Sagefern grieves for her mentor and is present at the emergency gathering with Dewstorm and Creamheart. When Depthstar questions the medicine cats about their attackers, Sagefern anxiously tells him one cat kept yowling "Death to the Clans!", referring to Bonfire. At the end of the gathering, Frostedstar looks down at Sagefern and thanks StarClan that Otterpelt had an apprentice.  (Shadows of Blood, chapter 23)

Sagefern visits ThunderClan multiple times after the attack to check on Spicewhisker and thinks he might not pull through.  (Shadows of Blood, chapter 26)

Ravenfeather tells Deserve he will try killing Sagefern, though he is unsuccessful.  (Shadows of Blood, chapter 26)

After the Battle

Sagefern is warmly speaking with Creamheart. She's amused at how talkative Cavernpaw is. (Winds of Darkness, chapter 6)

At the gathering, Sagefern is watching Cavernpaw bounce around excitedly. (Winds of Darkness, chapter 7)

Sagefern tells the medicine cats that they found Lemonsplash strangled by reeds in the river. She agrees with WindClan's idea to assign guards to their medicine dens. (Winds of Darkness, chapter 18)

At the gathering, Sagefern bows her head in grief at the news of Dewstorm's death. She says they'll never forget him and compliments Gingerfrost as a fine successor. (Winds of Darkness, chapter 25)

After the battle against Rosemary, in the RiverClan camp, Sagefern hosts the treatment of the wounded outside her den alongside the other medicine cats. She tends to a gash in Ivy's flank. (Winds of Darkness, chapter 29)