Jacks was born to Whittle and Sween Longtreader during the time of Morbin Blackhawk's rule. His time in the serenity of Nick Hollow was short-lived, however, as he was little more than an infant when his family's home was invaded by Redeye Garlackson. The whole family, save for his older siblings Heather and Picket, was abducted and transferred to the slave city of Akolan. There, Jacks was heavily indoctrinated by the Longtreader Command; because of this, he was extremely loyal to the Wrongtreaders and would keep a watchful eye on the comings and goings of his family, threatening to report any suspicious activity on their part.
On Victory Day, the day on which the indoctrinated younglings, including Jacks, were to be slaughtered and fed to Morbin, Heather helped her youngest brother to see the evil of siding with Morbin, and he allowed her to take him to the safety of the Seventh District.
Jacks subsequently formed a devout loyalty to The Cause, and aided his parents as they fought in the Siege of First Warren, including helping them rescue Heather and Smalls from the Tomb of Lander's Dragons. Following the War for All Natalia, Jacks joined his father in opening a school.
Jacks is seen to be held by his mother as Heather and Picket run back toward their elm tree home after their frightening ordeal with their starstick getting stuck in the maple by East Wood. Afterwards, when everyone is safely inside, Picket holds Jacks in his arms, and Heather remarks that she didn't have a way with him as Picket did. Picket then replies that Jacks' calmness was a result of the mutual promises of trust and loyalty they had made to one another--that he would always be there for Picket, and Picket would always be there for him. Not long afterward, Sween puts Jacks to bed, singing lullabies to him.
It was only the following day that he was captured along with his parents by Redeye Garlackson's wolves, and taken to Akolan. Heather and Picket were left not knowing whether he or their mother and father were alive or dead.
When Heather is finally reunited with her parents, she finds out that Jacks was attending the Akolan academy, and would return to stay at their home in District Four for two days.
She finally sees him again for the first time in a long time, when Heather and their father return from a secret Resistance meeting in the Seventh District. He chides his father and sister for being out after curfew, considering out loud whether he should tell his teacher about it. His mother then asks him not to do so, a plea to which he replies that he only wished to follow the rules most carefully. Much to Heather's and her parents' horror, Jacks then announces that he had been picked for a "special program," involving him being fed special foods and vegetables to prepare him for Morbin Blackhawk's table - a fate completely unknown to Jacks. Heather and her parents later have a conference, during which they discuss their options and determine to save Jacks from his terrible fate.
Upon the morrow of the next day, Heather takes Jacks out for a walk, to tell him a story about a miner who had forgotten who he was and had lost his way. When she finished, Jacks asked her whether he found his way home again, to which she replied that the miner only did so when he remembered who he was. Jacks frowns at the answer, and proceeds to say that she should get to her job in the hospital, as the morning was passing.
Later, as Heather returns to her home after her painful confrontation with Captain Vitton, she overhears a conversation between Harmony and Jacks. Harmony had been trying to find Heather, and was frustrated at her unsuccess in exacting an answer from Jacks (who only answered her questions by asking her why she wasn't at her job and why she was looking for his sister). In her agitation, she repeats her question in a ruder tone, even calling Jacks a "snotbag". Indignant, Jacks replies by telling her that Heather was at her job, and that Harmony should be as well; he then tells her promptly that he would report her and Heather to the authorities. He then slams the door in Harmony's face.
When Heather returns from the Seventh District, after attempting to heal The Tunneler, she finds Sween weeping in their home. When she asks what the matter was, her mother answers that Jacks was being held at the administration's headquarters for Victory Day, when the younglings would be killed to be turned into choice meals for Morbin.
After Heather is rescued from Captain Vitton by her father and the Commandant, she spots Jacks in the crowd forcibly gathered for Victory Day, all of whom were now attempting to escape Akolan with the assistance of the Resistance. He runs from her, but she catches up to him. Initially resisting her attempts to save him because of his trust of the administration, he eventually realizes the evil of Morbin, and together they make their escape from Morbin's minions by going down the aqueduct and running to the Lepers' District, through which Jacks makes his way to the Seventh District and safety along with many rabbits.
Jacks becomes a dedicated member of the Seventh District, even competing with his father as to who can throw message stones farther. He takes part in the Seventh District's efforts to convince the inhabitants of Akolan to join them in fleeing the city. He and his family then sail to First Warren, picking up Heather and Smalls from Forbidden Island as it crumbles. Following the War for All Natalia, he is reunited with Picket after the latter recovers from critical injuries sustained during the Siege of First Warren.
Jacks and his family sit together as guests of honor at the first Feast of the Mending, a year after the war ends. Jacks later joins his father in running a school, though Whittle is for a time occupied with writing The Rise and Fall of King Jupiter the Great. Jacks later attends a family gathering at Helmer's Farm, where he warmly greets his brother-in-law King Smalden.
Personality and traits
As an infant, Jacks was never more relaxed than when he was held by Picket. When he grew older, he was indoctrinated by those at the academy of Akolan to trust the administration and submit to slavery. This occurred in spite of his parents attempting to counteract his training. He was very loyal to the administration, attempting to observe all their rules with the utmost care, until Heather rescued him on Victory Day.
Heather's efforts to reach Jacks helped him start to see through the web of lies with which he had been ensnared. For a time he still struggled between the doctrines of the Wrongtreaders and his family's cause, but eventually became a loyal member of the Cause. He also became confident and somewhat competitive, believing he could exceed his father's performance in an identical task. Despite this, Jacks loved and respected his father, even working with him as he grew older.