Jojen is the younger brother of Meera Reed and is the eldest son and heir of Lord Howland Reed of Greywater Watch.
Bran Stark, Rickon Stark, Osha, Hodor, Summer and Shaggydog are fleeing to Castle Black following the Sack of Winterfell when Jojen first appears to Bran in a dream. Later he walks up to him while he is alone in the forest saying that he and his sister have been searching for him for a long time so that they can protect him. Osha surprises Jojen by putting a spear to the back of his neck, but Osha releases him when Meera suddenly appears with a knife to Osha's neck. Osha warns Jojen that Summer will protect Bran, should Meera harm him but Summer sniffs Jojen's hand and walks on. Jojen and Bran bond as they discuss their fathers when Jojen recalls that he has traveled in his mind to witness Robert's Rebellion in his dreams. Jojen gives cryptic information about Bran's powers as a warg. Osha grows increasingly resentful of Jojen.
Jojen and Bran share a greensight dream where Bran climbs a tree to follow a three-eyed raven, although Bran falls after Catelyn Stark appears repeating her warning in which she made him promise never to climb again - a promise Bran broke. Bran and Jojen wake in their camp in the woods, disappointed that he could not follow the three-eyed raven.
Jojen Reed has another vision which appears as a seizure. Jojen then tells Bran that in his vision he saw Jon Snow surrounded by enemies.
After seeking shelter in a derelict windmill during a rainstorm, the group notices a band of wildlings chasing down a old man. The sounds of thunder terrify Hodor, who shouts out in panic. Fearing discovery, Jojen tells Bran to silence Hodor, who keeps panicking. Bran unintentionally uses his Warg powers to render Hodor unconscious. With the wildlings still outside, Jojen convinces Bran to Warg through Summer and Shaggydog outside, who then maul to death some of the wildlings. While in control of Summer and Shaggydog, Bran saw Jon Snow outside fighting the wildlings. After this, Bran insists that he must go beyond the Wall to find the raven. However, he wants Rickon to be safe, so he tells Osha to take his brother with her to the holdfast of Greatjon Umber, a loyal bannerman of the Starks. Bran bids a tearful Rickon farewell, who leaves with Osha and Shaggydog, while Bran continues northward with Hodor, Summer and the Reed siblings.
At last, the group make it to the Wall and stay overnight in the Nightfort, an abandoned castle on the Wall that is rumored to be haunted. During the night, Jon Snow's fellow Night's Watch comrade Samwell Tarly, with Gilly and her child, emerge from a secret passageway. Samwell, noticing the gigantic Hodor and Summer, realizes who Bran is and offers to take them to Castle Black, but Jojen tells Sam that they are going beyond the Wall, as no force in the realm of Westeros could withstand the threat posed by the White Walkers. Sam reluctantly shows them the secret sally port and gives them the obsidian blades found north of the Wall, which he earlier used to slay a White Walker. That night, Bran, the Reeds, Hodor and Summer finally pass beyond the Wall.
When Bran becomes obsessed with warging Summer, Jojen is forced to warn him of the dangers that perhaps Bran will be trapped by his own powers. He emphasises that they need Bran to survive. Heading further North, Jojen helps Bran find a heart tree, which shows the young boy the way.
Later, Bran and his companions are resting near Craster's Keep. They hear the faint sounds of a baby's cries. Bran enters the mind of Summer to investigate where he finds Ghost, the direwolf of Jon Snow. However, before he can free Ghost, Summer is caught by a trap. At Meera's urgings, they go to rescue Summer and Ghost but are taken prisoner by Karl. While Hodor is being tormented by Rast and the other mutineers for pure amusement, Karl threatens to kill Jojen and Meera before Bran gives up his identity.
Jojen and the others are being held imprisoned in a tent. Karl enters the tent and ties up Meera and prepares to rape and torture her. Jojen begs for mercy and offers to help them, saying he possesses the sight. Karl refuses and just before he cuts Meera, Jon Snow and members of the Night's Watch attack the keep. Locke, who really serves Roose Bolton, searches for Bran and finds him and attempts to escape the keep with Bran. However, Jojen signals Bran to warg into Hodor, allowing him to save his own body through Hodor's. When Bran is about to get Jon's attention, Jojen arrives and intervenes, telling him that Jon will not let him search for the Three-eyed raven if he goes with Jon back to Castle Black. Bran agrees and prepares to leave.
The group arrives at the tree from Bran's vision, but they are ambushed by wights that emerge from beneath the snow. Jojen is grabbed by one of the wights, but Meera comes to his aid before he is dragged beneath the snow. Meera successfully protects him, but one of the seemingly defeated wights pulls a knife out and repeatedly stabs him. Jojen lives long enough to see a child of the forest, and tells his sister to go with Bran and the others. Before doing so, Meera mercifully cuts his throat. Soon after, the child of the forest uses her magic to burn Jojen's body to prevent its reanimation as another wight. The Three-Eyed Raven then reveals that Jojen knew that the quest would cost his life.
During Meera's rant at Bran, she mentions that Jojen, Summer and Hodor all died to make sure he survived for the Great War.
The only son of Howland Reed, lord of Greywater Watch who fought alongside Ned Stark during Robert's Rebellion, jojen experienced visions similar to Bran Stark's. Despite the careful protection of his sister Meera, Jojen was killed in a wight attack while traveling with Bran and his sister beyond the Wall.