At some point after Thaegan was given control over Ruby territory, Jin and Jod set up a home in a small valley in the territory. Their home was on a section of land surrounded by a ring of quicksand. They placed a bell and on half of a warning sign - which read "Ring and enter" - near the entrance to the valley to lure in unsuspecting passers-by who would fall into the quicksand trying to enter the area. Jin and Jod would then "rescue" and drug their captives before murdering and eating them. The only safe way to escape the ring was by using a series of hidden stepping stones. The stones were hidden halfway under the quicksand and surrounded by leaves with meaningless red symbols scrawled on them, another trick meant to fool their captives into falling back into the quicksand.
One of their many victims was Manus, a Ralad that Jin and Jod found too small to make a good meal. Instead, they kept him as a sort of pet until he managed to escape by using Jin and Jod's stepping stones.
Jin and Jod, along with their mother and siblings, were mentioned in the Enigmatic Giant's final riddle to Lief. They first appeared physically when Lief, Barda and Jasmine stumbled onto their home while travelling through the Ralad territory. Lief had found their sign while searching for firewood and called his friends over, only for the three of them to fall into the quicksand. Jin and Jod saved the trio and Jin introduced them as "Nij" and "Doj", respectively. The siblings took Lief and his companions into their home and Jin went off to prepare the meal while Jod gave them drugged drinks.
However, Lief inadvertently touched the Topaz on the Belt of Deltora, which cleared his mind and allowed him to see through their illusions. He guessed their true identities by remembering the Giant's rhyme and alerted Barda and Jasmine. The group managed to sneak out of the house when Jin and Jod heard their bell ring again and rushed out, excited at the prospect of a feast. The intruder turned out to be Manus, who had tossed a large rock into the quicksand to distract the monsters before racing into the house to try and free Lief, Barda and Jasmine. Jin and Jod caught up to him and chased him back out of the house, furious at the sight of their former slave. Jod managed to catch Manus with his hook, but Lief cut it in two with his sword and Manus managed to wordlessly tell Lief how to cross the stepping stones. Lief, Barda, and Manus made it across, but Jasmine was struck on the shoulder by Jin's axe, knocking her into the quicksand. Lief and Barda managed to free her when Kree arrived and distracted the duo, though his wing was broken in the process. Jin and Jod leapt after them, only to sink into the quicksand, much to their surprise and horror. After they sank to their doom, Jasmine revealed that she had moved the leaves, knowing that Jin and Jod would be too angry to notice that the pattern had changed.
They and their deaths are briefly mentioned again by Thaegan as part of her motivation for attacking Lief, Barda, Jasmine, and Manus at the Lake of Tears.
Jin was described in The Lake of Tears as being a bulky, ogre-like creature with sickly, greenish-white skin covered in black bristles. Her head was bald and sported three stubby horns. She had yellow tusks that jutted from her mouth and tiny eyes. When disguised by magic, Jin took the form of an overwight, elderly woman with twinkling, blue eyes and grey hair tied in a knot behind her head. She wore a long, blue dress and a white apron.
In the anime, Jin is a white tusked creature with blue eyes and three horns. Her human form was much smaller and more elf-like in appearance. She was not overweight, had pale skin and held some of her shoulder-length white hair back with a pink headband. She retained her blue dress, but did not have an apron. She also wore a pair of spherical earrings.
Jin and her brother appeared to be rather sadistic and intelligent in comparison to their other siblings. Rather than actively hunting, the pair set up an elaborate magical trap to catch prey with relative ease. They spoke very excitedly and openly to each other while luring their captives into a false sense of security, often smiling pleasantly while saying atrocious things, knowing that their language was normally disguised by magic. They even went so far as to put up embroidery on the wall of their home, which read "Live on evil"; when under the influence of their magic, the message became "Live no evil". Additionally, upon realising that Manus was too small to be a satisfying meal, Jin and Jod opted to keep him as a slave or pet rather than simply murder him.
Jin and Jod were capable of using magic to disguise their speech as a foreign language. In actuality, it was normal speech, but reversed, so that phrases like "Soon you can sleep forever" became "Reverof peels nac uoy noos". They were capable of disguising themselves as a sweet, kindly, human couple, as well as disguising their home — a dark, disgusting cell — as a lovely, warm home. Jin and Jod were quite skilled in deception, smiling pleasantly in their human forms and acting surprised by their "warning sign" being broken.
Jin was also apparently skilled at drugging the drinks she and Jod give to their captives and was the one who cooked the pair's meals. She was also very strong, as she helped Jod pull captives from the quicksand and was able to throw an axe with enough force to knock Jasmine over.
Jin and her brother both used a massive, hooked pole to "save" their intended prey from the quicksand ring. This pole was sliced in half by Lief when Jod attempted to use it to catch Manus. Jin brandished a massive axe while chasing Manus, but she threw it at Jasmine near the quicksand and no mention was made of her retrieving it. Jin and Jod also owned several massive kitchen knives and presumably the other equipment necessary to make stew.
When Lief imagined Jin and Jod's complete warning sign, the letter "S" was omitted from "quicksand".
When Jin heard Manus ring their bell and shouted to Doj that there was "More meat", "meat" was spelled backwards incorrectly, as "team" instead of "taem". This was also true when she warned Jod not to let Jasmine, Lief and Barda sink - "out" backwards was spelled "tou" instead of "tuo".
She is the only female child in Thaegan's family in the anime. In the books, Fie is confirmed to be female as well.