Reirei is a fairly slender jackal, with tan fur and black markings across her back and legs as well as on the top of her head. She has a beige underbelly, a beige muzzle, a black nose, and green eyes. Her chest is marked with several paler spots. She has a bushy tail with a black tip and a pair of large, pointed ears with small tufts of fur at their tips.
Reirei has been described as "scheming". She is cunning and devious, and has a knack for faking pleasantry and kindness, a skill that she teaches to her pups. Reirei takes pride in the craftiness of her kind, believing them to be smarter than other animals. She likes stealing from animals that she has gained trust in, and then insists that it was all a misunderstanding. Reirei is greedy, grasping, acquisitive, materialistic, and covetous, so she has no respect for the Circle of Life or Kupatana. However, she falters in the face of defeat, and will surrender if she sees no other options. She is also very wary of the Lion Guard and will not make any attempt to subdue them, and instead surrenders immediately.
Despite her scheming ways Reirei is also grateful to those who help her. Reirei is also known to underestimate her opponents.
Reirei is shown watching her son Dogo fool the Lion Guard into permitting him to enter the Pride Lands after they save him from Janja's Clan. She laughs, pleased that Dogo accomplished his task, and wakes her mate Goigoi to deliver the news. He goes to fetch their other sons, whilst Reirei begins to think of all the animals she can feast upon.
The Lion Guard takes Dogo to the Pride Lands, not knowing that Reirei and Goigoi are following them, and tell him that he may stay on a hillside before splitting up to patrol the Pride Lands. Reirei immediately greets her son and congratulates him, but is quick to ask why he is sitting on the hillside. Dogo explains that the Lion Guard told him to stay there, to Reirei's amusement. She tells him that jackals don't sit on hillsides, and announces that they should make themselves at home.
The jackal pups do as their mother says, choosing to sleep in the aardvarks' dens, much to the irritation of their former inhabitants. When Kion, Fuli, and Ono arrive to sort things out, Reirei and Goigoi approach them, introducing themselves as Dogo's parents. Kion asks which one of the jackal pups is Dogo, and Dogo approaches him cheerfully. Kion recalls that Dogo said he had no family, but Dogo protests, telling Kion that what he said specifically was that he was alone. Reirei adds that at the time, he had been. She assures Kion that it was all a misunderstanding, and he allows them to stay.
Later, as the jackal family walks through the Pride Lands, Reirei decides that they should help themselves to more of the Pride Landers' generosity. Dogo asks her if that will make Kion and the Guard mad, but Reirei explains that due to it being the day of Kupatana, they can do whatever they want. She teaches Dogo and her family how to get their way. This results in a number of a number of Pride Landers angry at the jackals for stealing from them, but when the Guard arrives, Dogo and Reirei once again insist that it was a misunderstanding, and they are permitted to stay in the Pride Lands. Reirei even talks Kion into considering allowing the jackals at Kupatana.
Reirei is seen watching the Pride Landers before Kupatana begins. She tells Goigoi that she's moved by all of the choices in prey, wondering where they'll begin. When the Kupatana begins, the jackals attack, with Reirei in the lead and Dogo at her side. The Lion Guard moves into action to stop the predators. Reirei chases after and catches a hyrax, but is attacked by Kion, who accuses her of lying to him. Reirei innocently asks if they'd made another mistake. Kion tells her that the jackals are going back to the Outlands. Reirei tries to talk her way out of it once more, but Simba roars angrily at her, and the jackal family flees.
Reirei steps outside of her den sniffs the air and realizes that she can detect the delicious scent of aardwolves. Excited, she attempts to awaken Goigoi, who, though first very sleepy, leaps awake at the word aardwolf, as Reirei predicted he would. She notes that it smells like a whole pack of them and that they had just moved in next door. Goigoi asks when the hyraxes moved out, and she reminds him that they didn't and decides to say hello to their new neighbors.
Reirei overhears Ogopa remarking that there's nothing to eat in their new home, and she comments that she wouldn't say that. She enters their cave and introduces herself and Goigoi as the folks next door. Ogopa explains that they thought the jackals were the Lion Guard, and Goigoi ducks behind Reirei, frightened. She kicks him away, and Haya explains that they gave the Guard the slip. She understands and reassures them that the jackals are the furthest thing from the Lion Guard. She inquires as to why they're fleeing the Guard, and when Ogopa says that they're mean and scary, Reirei enthusiastically agrees. Ogopa soon asks if Reirei will tell the Guard where they are, but Reirei tells her not to worry and promises that the Guard won't find hide nor hair of the aardwolves. She adds to Goigoi that the Guard might find a little hide.
Ogopa becomes confused at this, and Reirei explains that she only meant that they'll be good friends. She asks them if they know what friends do, and Goigoi answers that they have each other for dinner. Reirei kicks him viciously and informs the aardwolves that he meant to have them over for dinner. She sings We'll Make You a Meal, dancing and singing with Goigoi, to make the aardwolves happy and comfortable. When they finish, Ogopa exclaims that they're lucky to have selected the den that they did, and Reirei contradicts her, saying that she and Goigoi are the lucky ones.
Mjomba enters the den, and Reirei invites him in happily. He tells the aardwolves that they can come back to the Pride Lands, and as he explains, Reirei and Goigoi creep up behind them. She stops them just before they leave, reminding them that she thought they were going to have dinner where they were. Mjomba asks if she has any termites, and she answers that none of them will be leaving the cave hungry and that in fact, none were to leave the cave at all. She orders Goigoi to push, and he shoves a rock over the entrance of the cave, trapping them in. She decides to bring her sons the leftovers and springs at the aardwolves. Just as she is about to bite into an aardwolf, the Lion Guard breaks into the den, and Kion orders her to get away from her prey and pounces on her.
Pinned, Reirei remarks that it's nice of Kion to drop by, though she wishes that he had come later. Kion releases and tells her to go home. After exiting the den, Reirei breathes a sigh of relief but is then knocked into their own den by Goigoi. Bunga shuts them in, but Reirei tells him that she and Goigoi love it there. She asks for backup from her mate, who has already fallen asleep again.
Reirei is secretly watching Muhimu's Herd graze nearby when she slinks down to speak with her children. She tells Dogo and Kijana that it's time for them to try out a technique that they have been practicing - luring a young one away from the rest of the herd to strike it down while the older jackals chase away the older zebras. She puts her plan into action and, upon spotting a young zebra, directs her youngest children over to him.
Reirei chases the other zebras alone, when one of them catches their foot on a protruding rock and slams into the ground, skidding to a halt in front of a large boulder. Reirei approaches her, but Kion reveals himself from behind the boulder and warns Reirei that she's the last one left. She appears surprised by this revelation but is pinned to the ground by the young lion cub before she can do anything. Kion releases her and joins the herd which has finally calmed down. Bunga delivers her two youngest children back to her, while the others gather around Reirei. She overhears how Hamu kicked Dogo away, and after asking Kion if he heard what they just stated, Kion assures her that she'll be safe from the vicious zebras when she returns to the Outlands. Slightly irritated, Reirei calls for her kids to follow her. When Goigoi doesn't follow, she angrily calls for him as well. Later, Dogo and Kijana train under their mother's guidance. She orders them to get the little one away from the pack, but with only their father and two older siblings in front of them, they hesitate. Goigoi offers to play the role of the little one, which Reirei responds to warmly. She quickly urges her children to run him down and they do so, alarming Goigoi as they approach. Once they successfully pin their father down, Reirei praises their performance, believing that it's time for them to return to the Pride Lands. Kijana voices her concern over the Lion Guard, but Reirei tells her that she will deal with them herself.
Reirei returns to the Watering Hole and watches from behind a nearby rock. She orders her pack to move on since the older animals won't be good for training but recoils when she hears Muhimu mention the little ones. She overhears Twiga mention that they're at Hakuna Matata Falls, and decides that it would be perfect for her children. Before he can leave with them, she tells Goigoi to halt the Lion Guard whilst the rest of them go after the youngsters, assuring him that they'll leave him a tidbit before swiftly leaving with the kids.
At Hakuna Matata Falls, Reirei and her pack watch the youngsters play under the guidance of Bunga. Reirei tells her children not to worry about Bunga since she'll be taking care of him. Dogo asks his mother if they'll save some food for his father, and she replies that they will with insincerity. Reirei and her family soon step in to spoil the cheerful atmosphere, where Reirei pins Bunga to the ground. After the kids start to attack her children, Bunga briefly gets away from Reirei to cheer them on but is caught again shortly after, where the mother announces that she is positive that their training will secure their victory.
Soon, Bunga declares victory over Reirei's pups. She halts her attack in disbelief, and Bunga joins the children to charge the jackal family one last time. The Lion Guard arrive just in time to see the jackals' defeat. Reirei soon grabs Kion's attention, complaining about how her family has been treated and asking for his help. Kion is sure they can help, provided that they leave and never try to attack the kids again. When freed, Reirei claims that she doesn't wish to stay where she's not wanted, and the kids warn her away. She and her family than run back home, defeated.
Reirei and her pack chase some pangolins in the Pride Lands to a cliff edge, forcing them to curl up in balls. After scolding her youngsters for playing with them, Fuli and Ono arrive. Reirei calmly commands her family to scatter, rendering the outnumbered Fuli and Ono unable to catch any of them. Reirei then disregards her former advice to her kids, and the jackals attack Fuli by throwing the pangolins at her.
When the pangolins land, they uncurl. But when the jackals charge at them, they use their flatulence to ward them away. Reirei signals defeat, and the jackals retreat.
Reirei and her pack return to the Outlands, meeting up with Janja's Clan along the way. They return to the Outlands Volcano, where they excitedly inform Scar that the plan to break up the Lion Guard was a success. Scar explains that their first mission was merely a test and that their main objective would be in the next mission - eliminating Rafiki. When Janja and Reirei show confusion at this plan, referring Rafiki as An old monkey, Scar continues to inform them that Rafiki can sense all the Lions of the Past, including himself, something he does not want the Pride Landers to discover yet. Janja and Reirei then start to squabble over who will take out Rafiki and who will cause a distraction, but Scar grows tired of their pettiness, and sends Janja's clan out to take down Rafiki, who he informs them is meditating at Mapango Cliffs, while Reirei's pack distract the Lion Guard. Reirei proudly states that jackals always get the job done.
Outside, Janja taunts Reirei over Scar's decision. When Reirei states that jackals are the smartest, the two leaders start to argue that their kind is the smartest.
Reirei and her pack chase down some gazelles in a bid to get the Lion Guard's attention. When they cross a dense opening, Tamaa the drongo starts to impersonate the Lion Guard just outside, flying across to give a false impression that the full Lion Guard are surrounding the jackals. Although Reirei takes comfort in the fact that none of the Lion Guard members are going after Janja's clan, Goigoi reminds her how bad it is for them. But when Tamaa impersonates Kion's Roar, the jackals are shocked to find themselves still standing. During this time, Reirei notices Tamaa's tail feathers just outside the clearing and pins him down. It doesn't take long for Reirei to realize that Kion has tricked them, and the pack leaves to assist Janja's clan.
After getting back with Janja's clan, she and her pack participate in the battle against the Lion Guard, Tamaa, and Rafiki. However, after getting thrown around too much, Reirei surrenders, and she and her pack leave, along with Janja's clan.
Under Scar's order, Reirei and her family attack the Lion Guard as they make their way to the Outlands Volcano. She is caught off guard when Bunga uses his flatulence on them, and the Guard race past them.
Later, She and her family trap the Lion Guard in the volcano, with the rest of Scar's army. They corner the Lion Guard over a platform above the volcano, but Kion uses his Roar to push back Kenge, Ushari and the skinks. Trying to stop them from going further, Reirei and her family are up next but are also blasted away by the Roar.
Reirei and her pack target Kilio Valley as per Scar's orders. After setting the valley alight, Reirei's pack target Ma Tembo's Herd while the Lion Guard struggle to extinguish the blaze. When the Lion Guard notice their attack, Fuli holds back Reirei. Unable to fend off their attackers, the Lion Guard retreat with Ma Tembo's herd, leaving the Army of Scar members to watch menacingly as they leave.
Having won the battle, Janja declares the battle a victory thanks to the hyenas, causing Reirei to lash out and state that the jackals were responsible. The chain continues with Kiburi stating that the crocodiles were the main reason for success, followed by Mzingo who states it was the vultures. When Reirei questions them on their intelligence with Mwoga still carrying a blazing stick, the vulture promptly drops it on the ground. Scar appears from the small flames to give them their next order. He explains how they will be staying in the valley and will take the Pride Lands piece by piece.
All the animals agree that the valley is a dump, but when Janja offers to rule over them, he causes Reirei and Mzingo to argue over leadership, with Reirei stating that she's the smartest of them all and hence will be their leader.
Later, she fights with one of Kiburi's crocodiles and one of Mzingo's vultures for the leadership of the valley.
Scar tries to take over other parts of the Pridelands but his plains seem to fail. After hearing that the nice hyena Jasiri was still around and she made a Hyena Resistance to stop Scar. He orders his army to get rid of her clan. Kion and the guard show up and Kion uses the roar to blow the army away.
Reirei, Goigoi and some other adult jackals find a missing calf who has strayed in the Outlands. When the Lion Guard try to intervene, Reirei warns them to back off since they found it first. Kion, Beshte, and Ono catapult some nearby fruits across to them. Reirei and the other jackals make a hasty retreat to the Outlands.
She appears trapped on a log in the river and she asks Goigoi and another jackal to go get help. They do so by asking the Lion Guard for help. In Beshte's side of the story he goes through a water labyrinthine to find Reirei meanwhile, in Ono's side of the story he spots Reirei from above heading for Makuu's float but thanks to the egret she's safely guided through. In the end, she is pushed safely back to shore but very angry; however, it's not at the Lion Guard but the jackals for calling their enemies for help and chases them in anger.